GAUHATI, India — Bombs planted in cars and rickshaws ripped through crowded markets in a coordinated attack Thursday in India's volatile northeast, killing at least 76 people and wounding more than 300.
The scale and planning behind the 13 blasts surprised authorities, who struggled to determine who was behind the attacks _ among the worst in a region plagued by separatism, ethnic violence and Islamic militants.
The largest explosion took place near the office of Assam state's top government official, leaving bodies and charred, mangled cars and motorcycles strewn across the road.
Bystanders dragged the wounded and dead to cars that took them to hospitals. Police officers covered charred bodies with white sheets in the street.
Later, dozens of people angry over the blasts took to the streets of the state capital, Gauhati, stoning vehicles and torching at least two fire engines. Police imposed a curfew on the city and closed roads leading in and out of the area.
Seventy-six people were killed, with more than a dozen dying from their injuries overnight Thursday, said Subhash Das, a senior official in the state's Home Ministry, on Friday. Some 300 people were wounded by the bombs that went off before noon, he said.
Officials blamed the largest separatist group, the United Liberation Front of Asom, for the blasts. "The needle of suspicion is on ULFA," said Assam government spokesman Himanta Biswa Sharma.
However, the group has never carried out an attack of this size and complexity, which closely resembles bombings that have rocked other Indian cities this year. Those attacks were blamed on Islamic militants.
"Going by the nature, planning and magnitude of the blasts we need to find out if ULFA has been assisted by other terror groups ... at home or abroad," said Das.
Anjan Borehaur, a spokesman for the United Liberation Front of Asom, denied his group had any role in the attacks.
India's northeast _ an isolated region wedged between Bangladesh, Bhutan, China and Myanmar with only a thin corridor connecting it to the rest of India _ is beset by dozens of conflicts. More than 10,000 people have died in separatist violence over the past decade in the region.
In July, at least 49 people were killed in violence between members of the Bodo tribe and recent migrants to the area, most of whom are Muslims.
The region is also home to dozens of separatist groups who accuse the government of exploiting the area's natural resources while doing little for the indigenous people _ most of whom are ethnically closer to Burma and China than to the rest of India.
U.S. Ambassador David Mulford condemned the latest attack.
"I send condolences to the people of India. Americans share their sorrow and outrage at these horrific attacks on innocent people," he said.
TV footage showed firefighters spraying streams of water at charred, twisted cars and motorcycles at the site of the largest blast outside the secretariat, housing the offices of the state's chief minister.
"I was shopping near the secretariat when I heard three to four loud explosions. Windowpanes in the shops shattered and we fell to the ground as the building started shaking," said H.K. Dutt, who was hit by shrapnel.
"I stood up and saw fire and smoke billowing out, then I looked down and saw blood on my shirt," he said.