Peggy Renner-Howell lays flowers at a makeshift memorial near the Sikh Temple of Wisconsin in Oak Creek, where a gunman killed six people this past Sunday.

Oak Creek, Wisconsin - A small United States community on Tuesday struggled to understand how a racist former soldier turned white power punk singer came to shoot six unarmed people at a suburban Sikh temple.

Teddy bears and flowers surrounded a makeshift memorial of six wreaths mounted on white stakes with the names and ages of each of the shooter's victims at the temple Oak Creek, a suburb of Milwaukee, Wisconsin.

Peggy Renner-Howell, 52, stood with her head bowed and her face clenched in sadness after laying white flowers at the food of each wreath.

“I'm totally devastated by what happened here,” she said. “I'm just hoping and praying the victims and the families of the victims can find some peace.”

Wade Michael Page, 40, burst into the temple with a 9mm handgun and several clips of ammunition - all purchased legally - and opened fire on worshippers attending a Sunday service, authorities said.

Special Agent Teresa Carlson, head of the Federal Bureau of Investigation's Milwaukee office, said the suspect - killed at the scene during a shootout with police - is now the subject of a “domestic terrorism” probe.

“We are looking at ties to white supremacist groups,” she told reporters, noting that the FBI did not have an active file on Page before the incident.

“No law enforcement agency had any reason to believe he was plotting anything,” she said.

But the Southern Poverty Law Centre, a civil rights group, branded Page a “frustrated neo-Nazi who had been the leader of a racist white-power band”, and the SITE Intelligence Group said he was an active skinhead.

A former army buddy, Christopher Robillard, told CNN that Page had spoken of “racial holy war, like he wanted it to come”, but added that he never thought the suspected gunman would act on his rhetoric.

Page was a member of the Hammerskins Nation, a group that describes itself on its website as a “leaderless group of men and women who have adopted the White Power Skinhead Lifestyle”, SITE said in a report.

Page “engaged in extensive online activity” and maintained user accounts on “some of the most prominent white supremacist forums”, SITE said, adding that he issued messages “urging active resistance 'regardless of the outcome’”.

The Southern Poverty Law Centre said the ex-soldier had recently been the leader of the three-man hardcore punk band End Apathy.

Photographs of the band on its Myspace webpage showed Page with a shaved head and Gothic tattoos all over his body.

Band members were shown performing in front of extremist flags, including one bearing a Nazi swastika.

Page served as a US military “psychological operations specialist” between April 1992 and October 1998, ending his career at the base at Fort Bragg, North Carolina, home to the US Army's airborne forces and Special Operations Command.

He was a qualified parachutist who received several good conduct awards and a National Defence Service Medal, but never won significant promotion.

The Indian-American community held a candlelight vigil late on Monday at a temple not far from the scene of Sunday's carnage.

Mourners earlier packed the temple to pay their respects. Those without head coverings, including Wisconsin Governor Scott Walker, were given scarves.

“We need this,” Harsimran Kaur, 30, said of the service. “It's been chaos. We have suffered so much.”

The dead were identified as Paramjit Kaur, a 41-year-old woman, Sita Singh, 41, Ranjit Singh, 49, Satwant Singh Kaleka, 65, Prakash Singh, 39 and Suveg Singh, 84, all men. Singh is a common surname in the Sikh community.

Kaleka's son Amardeep hailed his father as a “hero through and through” for confronting the attacker with the only weapon at his disposal - a blunt ceremonial knife - and stalling his progress, perhaps saving a few lives. - Sapa-AFP