MILWAUKEE -- The FBI says the motive behind the shootings at a Sikh temple that left six worshippers dead remains unknown but authorities still haven't identified anyone other than the gunman as being responsible.

FBI Special Agent in Charge Teresa Carlson also told a Wednesday news conference that investigators determined gunman Wade Michael Page died of a self-inflicted gunshot wound to the head after he was shot by police. Authorities previously said an officer had fired the fatal shot.

Carlson says federal officials had not opened any investigation into Page before Sunday's shooting. She says investigators are interviewing dozens of people who have known Page as they work to determine for a possible motive.

Earlier on HuffPost:

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  • In this undated combo photo composed of two images provided by the family, Indian Ranjit Singh, right, and Sita Singh who were killed in the shooting attack at a Sikh temple in Wisconsin are seen. The Indian born brothers were both killed in the shooting attack Sunday. (AP Photo)

  • Indian relatives of brothers Sita and Ranjit Singh who were killed in the shooting attack at a Sikh temple in Wisconsin, look at family photos at the family home in New Delhi, India, Tuesday, Aug. 7, 2012.

  • Ranjeet Singh

    In this undated family photo released Tuesday, Aug. 7, 2012, Indian Ranjeet Singh, who was killed in the shooting attack at a Sikh temple in Wisconsin, is shown. Singh, one of the victims of a shooting attack at a Sikh temple in the United States, never came home to India even once in 16 years, working at a grocery store during the week and volunteering at the Sikh gurdwara on weekends. He promised his family in India he was doing what had to be done to get a green card so they could come join him in the United States. (AP Photo/Ranjeet Singh family)

  • Indian Lokinder Kaur, third from right, mourns with her daughters Jasbir Kaur, 24, fourth from right, and Jaspreet Kaur, 21, second right, as they gather with other relatives at the family home in New Delhi, India, Tuesday, Aug. 7, 2012. Lokinder Kaur's husband Ranjeet Singh, one of the victims of a shooting attack at a Sikh temple in the United Staes, never came home to India even once in 16 years, working at a grocery store during the week and volunteering at the Sikh gurdwara on weekends. He promised his family in India he was doing what had to be done to get a green card so they could come join him in the United States. (AP Photo/Kevin Frayer)

  • Sita Singh

    In this undated family photo released Tuesday, Aug. 7, 2012, Indian Sita Singh, who was killed in the shooting attack at a Sikh temple in Wisconsin, is seen. Singh was killed during the attack on Sunday alongside his brother Ranjeet Singh who he had recently joined in the United States. (AP Photo/Seeta Singh family)

  • Sita and Ranjeet Singh

    Indian friends and relatives of Sita Singh who was killed in the shooting attack at a Sikh temple in Wisconsin, visit the family home in New Delhi, India, Tuesday, Aug. 7, 2012. Singh was killed alongside his brother Ranjeet Singh who he had recently joined in the United States during the attack on Sunday. (AP Photo/Kevin Frayer)

  • Indian Surinder Kaur, center, the wife of Sita Singh who was killed in the shooting attack at a Sikh temple in Wisconsin, is comforted by her son Armeet and daughter Sarabjit, second right, at the family home in New Delhi, India, Tuesday, Aug. 7, 2012. Sita Singh was killed alongside his brother Ranjeet Singh who he had recently joined him in the United States during the attack on Sunday. (AP Photo/Kevin Frayer)

  • Suveg Singh

    This undated photo provided by Mandeep Singh shows Suveg Singh Khattra. Balginder Khattra of Oak Creek, Wis. said Monday, Aug. 6, 2012, that his 84-year-old father, Suveg Singh Khattra, was among the dead in Sunday's shooting at a Sikh temple in Oak Creek, Wis. (AP Photo/Courtesy Mandeep Singh)

  • Indian Surinder Kaur, center, the wife of Sia Singh who was killed in the shooting attack at a Sikh temple in Wisconsin, is comforted by her son Armeet and daughter Sarabjit, right, at the family home in New Delhi, India, Tuesday, Aug. 7, 2012. Seeta Singh was killed alongside his brother Ranjeet Singh who he had recently joined in the United States during the attack on Sunday. (AP Photo/Kevin Frayer)

  • Harinder Kaur Rakhra, left, sister of Satwant Singh Kaleka who was killed in the shooting attack at a Sikh temple in the U.S. state of Wisconsin, is consoled by Seema Sharma, a local politician in Patiala, India, Monday, Aug. 6, 2012