The gunman who killed six people at a Sikh temple in southern Wisconsin was a former US serviceman, a law enforcement official has said.
The shooter had links to racist groups, a monitor of extremists said.
Wade Michael Page (40) is suspected of shooting
dead six people and seriously wounded three, including a police officer, at the Sikh Temple of Wisconsin yesterday as worshippers prepared for religious services. Police shot dead the gunman.
The man was discharged from the US Army in 1998 for 'patterns of misconduct,' including being drunk on duty, military sources said. He served in the military for six years but was never stationed overseas, was a psychological operations specialist and Hawk Missile System repairman who was last stationed at Fort Bragg, North Carolina.
In June 1998 he was disciplined for being drunk on duty and had his rank reduced from sergeant to specialist. He was not eligible to re-enlist, the sources said.
Authorities said they were treating the attack as an act of domestic terrorism.
The man had been a member of the racist skinhead band End Apathy, based in Fayetteville, North Carolina, in 2010, said Heidi Beirich, director of the intelligence project at the Southern Poverty Law Centre in Montgomery, Alabama.
He also tried to buy goods from the National Alliance, a neo-Nazi group, in 2000, she said.
US president Barack Obama said that Americans need to do more "soul searching" to find ways to reduce violence in the wake of the shooting spree.
"All of us recognize that these kinds of terrible, tragic events are happening with too much regularity," Mr Obama said when asked whether further gun control measures were needed.
He said elected officials and community leaders must come together to discuss what should be done.
Mr Obama said federal authorities had not yet determined what motivated the gunman but that if it turned out to be the "ethnicity of those who were attending the temple, I think the American people immediately recoil against those kinds of attitudes."
Police were searching an apartment at a duplex in the Cudahy neighbourhood near Milwaukee, presumed to be the residence of the gunman.
Generators and floodlights were set up along the street and a bomb squad was on the scene.
The names of the victims were not made public pending notification of relatives, although members said the president of the congregation and a priest were among the victims.
Jagjit Singh Kaleka, the brother of the president of the temple, who was among the six Sikhs killed, said he had no idea what the motive was for the attack.
"But we know the more assault weapons we distribute the more situations like this we will have," he said.
The gunman had used a 9mm semi-automatic pistol, which was recovered at the scene. Police were trying to track the origin of the weapon.
Wisconsin has some of the most permissive gun laws in the country. It passed a law in 2011 allowing citizens to carry a concealed weapon.
The attack came just over two weeks after a gunman killed 12 people at a theatre in
Aurora, Colorado, where they were watching a screening of new Batman movie "The Dark Knight Rises." I
American Sikhs said they have often been singled out for harassment, and occasionally violent attack, since the Sept. 11 attacks because of their colourful turbans and beards.
Some witnesses to the Wisconsin shooting said the suspect had a tattoo marking the 2001 attacks. Authorities confirmed he had tattoos but said they were not sure exactly what the tattoos illustrated.
There are 500,000 or more Sikhs in the United States but the community in Wisconsin is small, about 2,500 to 3,000 families, said local Sikhs..
The Sikh faith is the fifth-largest in the world, with more than 30 million followers. It includes belief in one God and that the goal of life is to lead an exemplary existence.
The temple in Oak Creek was founded in October 1997 and has a congregation of 350 to 400 people.
"These people were going to church. Two weeks ago, it was people going to a movie. When is it going to end?" said Ray Zirkle, who came from Racine, Wisconsin with his wife to light votive candles near the site of the shooting.
Reuters