FBI agent Teresa Carlson told a news conference at the agency's Milwaukee office Wade Michael Page shot himself in the head after he was shot in the stomach by an Oak Creek police officer who was one of three people critically wounded in the incident at the Sikh Temple of Wisconsin, the Milwaukee Journal Sentinel reported.
"The evidence indicates that the second responding officer who shot Page in the stomach, thereby neutralizing the threat -- and by the way, I've seen the video, it is an amazing shot. And thank goodness. Subsequent to that wound, it appears that Page died of a self-inflicted gunshot wound to the head," Carlson said.
Carlson said there is no evidence anyone else was involved in Page's actions.
Also Wednesday, President Obama called Indian Prime Minister Manmohan Singh to give his condolences for the death of Indian nationals at the temple, presidential spokesman Jay Carney told reporters on Air Force One. Carney said the president made the call from the plane.
Obama told Singh, a Sikh and the first non-Hindu to serve as prime minister in India, that both countries are committed to religious freedom, Carney said.
Police earlier confirmed Page's former girlfriend was arrested on suspicion of being a felon possessing a firearm.
Misty Cook, 31, of South Milwaukee was arrested after police found a gun at her apartment, which she shared with Page until they broke up in June and he moved to nearby Cudahy, police said.
Cook cannot legally possess a gun because she has a felony conviction for fleeing and eluding police in Milwaukee County.
The Milwaukee County district attorney's office will review the case. South Milwaukee police also consulted with the FBI, which is leading the investigation.
Fox News Channel said the weapon was not related to Sunday's temple shooting in which Page killed five worshipers and a police officer.
The Anti-Defamation League, which monitored Page and Cook for years, said Cook was associated with a group called Volksfront, which anti-hate groups describe as a racist neo-Nazi organization.
Volksfront, also known as Volksfront International, describes itself as an international fraternal organization for persons of European descent. The group told the Journal Sentinel Cook has not been a member since 2008 and her relationship with it could be described as "actively hostile."
The ADL says the group is "one of the most active skinhead groups in the United States." The Southern Poverty Law Center, which also monitored Page, includes Volksfront on its list of hate groups. Volksfront disputes the designation.
The Journal Sentinel reported Wednesday Cook worked at a restaurant about a block away from the Oak Creek Sikh temple Page attacked.
Page, who had a misdemeanor criminal record, legally purchased the gun used in the temple shooting.
Before her arrest, Cook told the Journal Sentinel by e-mail she did not wish to be interviewed.
"In light of this senseless tragedy, I must respectfully decline any requests for comments," she wrote. "If I could say something to ease the pain of the victims and their families I would gladly do so. Unfortunately words do not begin to heal the pain they are going through. I ask that you please respect my privacy in dealing with this issue as it is a great struggle for me."
In an e-mail to the Los Angeles Times, Cook said the emphasis should be on the "heroes" of the killing. She mentioned Satwant Singh Kaleka, who tried to hold off Page with a knife, giving his wife and others time to hide, and police officer Brian Murphy.
"The reaction of the Sikh community around the world has been admirable," Cook said. "Their advocation for education and understanding is something we should all try to emulate. The responding officers, especially Brian Murphy, are heroes in my book for preventing further bloodshed."
The newspaper said Cook and Page were active participants in an online message forum for a white supremacist group, using the screen names "Luluroman," which the ADL says Cook used as a handle, and "End Apathy," which the civil rights group says Page used. End Apathy was the name of his skinhead band.
"End Apathy" posted more than 200 times, beginning in 2010, the newspaper said. "Luluroman" posted nearly 800 times, beginning Dec. 29, 2009.
The ADL says Cook may be the reason why Page moved to the Milwaukee area nine months ago, the Journal Sentinel reported.