JERUSALEM — Devastated mourners grasped at dirt atop fresh graves and screamed in agony Friday as they buried the five Israeli victims of a bombing in Bulgaria – an attack that Israel has blamed on Iran and its proxy group Hezbollah.

Two days after the deadly blast in a popular vacation spot, investigators in Bulgaria and in several other countries were still struggling to confirm the attacker's identity.

Bulgarian prosecutors said the attacker had short hair, not the long hair seen in the security video footage captured of him at the airport. A witness said he appeared to be wearing a wig.

The victims' coffins were received early Friday in a military ceremony at Israel's international airport. Seventeen Israelis remain in hospitals.

Childhood friends Itzik Kolengi, 28, and Amir Menashe, 27, were buried in the central Israeli town of Petah Tikva.

Kolengi's wife, Gilat, was wounded in the attack and remains hospitalized. The couple has an infant daughter.

"I promise you that the family and I will watch forever over your wife, Gilat, and your amazing daughter, Noya, who looks exactly like you, and we'll raise her just as you would have wanted," Kolengi's brother David said during his eulogy.

Menashe's wife, who was also wounded in the attack, attended the funeral in a wheelchair. They too have an infant son.

Nearby, in Rishon Lezion, hundreds of mourners joined the family of Cochava Shriki, a 42-year-old woman who had recently become pregnant after years of fertility treatments.

In the northern Israeli town of Acre, Maor Harush, 26, and his close friend Elior Price, 24, were laid to rest. A third friend remains hospitalized in serious condition.

Israeli and American officials have blamed the Iran-backed Lebanese militant group Hezbollah for Wednesday's bombing, which killed five vacationing Israelis, along with a Bulgarian bus driver and the attacker, in the Black Sea resort town of Burgas.

In TV interviews Friday, Defense Minister Ehud Barak said he was certain who carried it out.

"Hezbollah is behind the attack, it was part of a series of attacks," he told Israel's Channel 2 TV. "We know that Iran is behind it all. What we don't know is who the actual man is."

Iran denied responsibility for the attack, which threatened to further escalate a shadow war between the two countries over allegations that Tehran is trying to build nuclear weapons. Iran says its atomic program is for peaceful purposes only.

Security camera footage from before the attack showed the suspected bomber wandering in and out of the terminal, wearing a baseball cap over long hair, a T-shirt and plaid shorts, with a bulky backpack.

Interior Minister Tsvetan Tsvetanov told reporters the bomb was in the backpack and detonated in the luggage compartment of the bus. The bomber was believed to have been about 36 years old and had been in the country between four to seven days, he said.

He later said in an interview with state TV that the blast was caused by 3 kilograms (6.6 pounds) of TNT powder.

Bulgarian prosecutors said the man tried to rent a car in the days before the bombing but was turned down because his ID appeared suspicious. Authorities have examined his fingerprints, his DNA and his fake Michigan driver's license.

They also said the man actually had short hair. It was not clear if he was wearing a wig, or if he had a haircut after the airport footage was taken.

Afrodita Petrova, the owner of the car rental company, told Bulgarian National TV that the suspect had short dark hair when visiting the office. She said he was the same person from the video camera footage and appeared to be wearing a wig.

"He spoke English with an Arab accent," she said.

Tsvetanov said the investigation had ruled out that the bomber was a Bulgarian citizen, but did not say how authorities know that. He said the investigation had also ruled out that the bomber was Mehdi Ghezali, a Swedish citizen and former Guantanamo detainee whom authorities had previously fingered as the bomber.

"Now we are focused on finding out the identity of the suicide bomber and his possible whereabouts ahead of the blast," Tsvetanov said.

Police and prosecutors refused to give any more information, saying it would compromise the ongoing investigation.

Israel has attributed a series of attacks on its citizens around the world in recent months to Iran and its proxies.

The Islamic militant group has not commented on the attack.

Iranian Foreign Ministry spokesman Ramin Mehmanparast called the accusation "baseless."

The U.S. intelligence community has a "high degree of confidence that this was carried out by Hezbollah," presumably by a cell located in Bulgaria, said an official who spoke on condition of anonymity to discuss intelligence matters. "This was researched and target was prepped," the official said, hallmarks of the discipline and expertise of the group.

However, Pentagon press secretary George Little said Friday the U.S. government has not established with certainty who was behind the attack.

"The attack does bear some of the hallmarks of Hezbollah, but we are not in a position to make any final determination," Little said. He declined to say what aspect of the attack resembled the methods or other features of Hezbollah.

Israel has officially issued a complaint with the U.N. Security Council, accusing Iran of responsibility for the attack. Israeli representative Haim Waxman wrote the Security Council president that the attack in Bulgaria was part of an international terrorist campaign against Israelis and Jews worldwide, led by Iran and Hezbollah.

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Associated Press writers Veselin Toshkov in Sofia, Bulgaria, Edith M. Lederer at the United Nations, and AP intelligence writer Kimberly Dozier in Washington, D.C., contributed to this report.

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  • A Israeli survivor from a bombing in Bulgaria that killed seven people on Wednesday, cries as he arrives at the Ben Gurion airport in Tel Aviv, Israel, Thursday, July, 19, 2012. (AP Photo/Dan Balilty)

  • Israeli women whose relatives were among the victims of a bombing in Bulgaria that killed seven people on Wednesday, July 18, 2012 wait for their arrival at the Ben Gurion airport in Tel Aviv, Israel, Thursday, July, 19, 2012. (AP Photo/Dan Balilty)

  • Relatives mourn Maor Harush who was killed in a suicide bombing in Bulgaria during his funeral in Acco, Israel, Friday, July 20, 2012. (AP Photo/Ahikam Seri)

  • Relatives mourn Maor Harush who was killed in a suicide bombing in Bulgaria during his funeral in Acco, Israel, Friday, July 20, 2012. (AP Photo/Ahikam Seri)

  • Family and friends attend the funeral of Itzik Kolengi, 28, who was killed and his wife injured in a suicide bombing in Bulgaria Wednesday in Petah Tikva, Israel, Friday, July 20, 2012. (AP Photo/Dan Balilty)

  • Relatives mourn Maor Harush who was killed in a suicide bombing in Bulgaria during his funeral in Acco, Israel, Friday, July 20, 2012. (AP Photo/Ahikam Seri)

  • People carry the body of Itzik Kolengi, 28, who was killed and his wife injured in a suicide bombing in Bulgaria Wednesday in Petah Tikva, Israel, Friday, July 20, 2012. (AP Photo/Dan Balilty)

  • Family and friends attend the funeral of Itzik Kolengi, 28, who was killed and his wife injured in a suicide bombing in Bulgaria Wednesday in Petah Tikva, Israel, Friday, July 20, 2012. (AP Photo/Dan Balilty)

  • Relatives cry over a coffin of victims killed in bombing in Bulgaria after the remains arrived at Tel Aviv airport, Israel, Friday, July, 20, 2012. (AP Photo/Dan Balilty)

  • Israeli soldiers carry the coffins of people killed in a bombing in Bulgaria as the remains arrived back at an airport in Tel Aviv, Israel, Friday, July 20, 2012. (AP Photo/Dan Balilty)

  • Israeli soldiers carry the coffins of people killed in a bombing in Bulgaria as the remains arrived back at an airport in Tel Aviv, Israel, Friday, July 20, 2012. (AP Photo/Dan Balilty)

  • Israeli soldiers carry a coffin of victims who were killed in bombing in Bulgaria after the remains arrived at Tel Aviv ariprt, Israel, Friday, July, 20, 2012. (AP Photo/Dan Balilty)

  • Israeli soldiers carry a coffin of victimes killed in bombing in Bulgaria after the remains arrived at Tel Aviv airport, Israel, Friday, July, 20, 2012. (AP Photo/Dan Balilty)

  • Relatives react as the coffins of people killed in a bombing in Bulgaria arrived back at an airport in Tel Aviv, Israel, Friday, July 20, 2012. (AP Photo/Dan Balilty)

  • An Israeli family cries during a military ceremony for the victims who were killed in an attack in Bulgaria, at Tel Aviv airport, Israel, Friday, July, 20, 2012. (AP Photo/Dan Balilty)

  • Relatives sit in front of the coffins of people killed in bombing in Bulgaria after the remains arrived at Tel Aviv airport, Israel, Friday, July, 20, 2012. (AP Photo/Dan Balilty)

  • This image taken from security video provided by the Bulgarian Interior Ministry Thursday, July 19, 2012 purports to show the unidentified bomber, center, with long hair and wearing a baseball cap, at Burgas Airport in Burgas, Bulgaria, on Wednesday, July 18, 2012. (AP Photo/Bulgarian Interior Ministry)

  • This image taken from security video provided by the Bulgarian Interior Ministry Thursday, July 19, 2012 purports to show the unidentified bomber, center, with long hair and wearing a baseball cap, at Burgas Airport in Burgas, Bulgaria, on Wednesday, July 18, 2012. (AP Photo/Bulgarian Interior Ministry)

  • Israelis move through the departure terminal at Ben-Gurion International Airport in Tel Aviv, Thursday, July, 19, 2012. (AP Photo/Dan Balilty)

  • Smoke rises into the sky after an explosion at Burgas airport, outside the Black Sea city of Burgas, Bulgaria, some 400 kilometers (250 miles) east of the capital, Sofia, Wednesday, July 18, 2012. A bus carrying young Israeli tourists in a Bulgarian resort exploded Wednesday, killing three people and wounding at least 20, police said. Witnesses told Israeli media that the huge blast occurred soon after someone boarded the vehicle. (AP Photo/ Burgasinfo) BULGARIA OUT

  • An unidentified injured Israeli tourist is carried in front of Borgas hospital after an explosion at Burgas airport, outside the Black Sea city of Burgas, Bulgaria, some 400 kilometers (250 miles) east of the capital, Sofia, Wednesday, July 18, 2012. (AP Photo/ Bulphoto Agency) BULGARIA OUT

  • Unidentified Israeli tourist is helped as she arrives to Bourgas hospital after a bus carrying Israeli tourists in the Bulgarian resort city of Bourgas exploded Wednesday, July 18, 2012, killing at least three people and wounding more than 20 others, police said. (AP Photo/ Bulphoto Agency)

  • An Israeli woman wounded in a bombing in Bulgaria that left five Israeli tourists dead on Wednesday is comforted by a medic at Soroka hospital in the southern city of Beersheva, Israel, Thursday, July 19, 2012. (AP Photo/Tsafrir Abayov)

  • A damaged bus is transported out of Burgas airport, Bulgaria, Thursday, July 19, 2012 a day after a deadly suicide attack on a bus full of Israeli vacationers. (AP Photo/ Impact Press Group)

  • A damaged bus is transported out of Burgas airport, Bulgaria, Thursday, July 19, 2012 a day after a deadly suicide attack on a bus full of Israeli vacationers. (AP Photo/ Impact Press Group)

  • A Jewish man reads prayers during a mourning ceremony at a synagogue in Sofia, Thursday, July 19, 2012. (AP Photo/Valentina Petrova)

  • Bulgaria's Interior Minister Cvetan Cvetanov, center, speaks during a press conference at Burgas airport, Bulgaria, Thursday, July 19, 2012 a day after a deadly suicide attack on a bus full of Israeli vacationers. (AP Photo)

  • Bulgaria's Interior Minister Cvetan Cvetanov, center, speaks during a press conference at Burgas airport, Bulgaria, Thursday, July 19, 2012 a day after a deadly suicide attack on a bus full of Israeli vacationers. (AP Photo)