A 40-year-old ex-soldier called Wade Michael Page has been identified as the suspect who shot dead six in a Sikh temple in Oak Creek, Wisconsin, on Sunday.
Page was killed by armed police after the rampage, during which three others were critically injured, including a police officer.
According to his Myspace profile page, Page played in a band called End Apathy.
He wrote on his bio: "The music is a sad commentary on our sick society and the problems that prevent true progress."
ABC News reported sources as saying that the suspect was a "white supremacist" and "a skinhead".
Fox News, meanwhile, said that Page once served in the US Army and was based in Fort Bragg in North Carolina.
According to the BBC, Page had been demoted.
The Southern Poverty Law Center, a group that describes itself as being dedicated to fighting bigotry and hatred, described Page as "a frustrated neo-Nazi who had been the leader of a racist white-power band".
A motive for the attack has not emerged yet.
Photos from the scene: