US President Barack Obama has said "soul searching" is needed on how to reduce violence following a second mass shooting event in the US in a month.
Wade Michael Page, 40, killed six and injured three at a Sikh temple in near Milwaukee, Wisconsin on Sunday.
He was shot dead by police in the temple's car park during the attack.
Officials say they are investigating reports that Page had white supremacist links, and the FBI is treating the attack as possible domestic terrorism.
The temple attack follows a shooting in Aurora, Colorado at a midnight screening of the new Batman film on 20 July. Twelve people were killed and 58 were injured in the attack.
"All of us recognise that these kinds of terrible, tragic events are happening with too much regularity for us not to do some soul searching to examine additional ways that we can reduce violence, " Mr Obama said during an unrelated bill signing on Monday.
Mr Obama has pledged to work with members of both political parties and civic organisations to reach a consensus on the matter, but has not given details.
Debate on gun control issues has featured very little during the US presidential campaign, which has mainly focused on the economy, correspondents say.
'Ambushed' The gunman opened fire at the Sikh Temple of Wisconsin in Oak Creek as dozens of people were preparing for a service on Sunday morning.
Oak Creek Police chief John Edwards told a Monday morning news conference they were confident Page was the only shooter.
The victims were identified on Monday as Sita Singh, 41, Ranjit Singh, 49, Satwant Singh Kaleka, 65, Prakash Singh, 39, Paramjit Kaur, 41 and Suveg Singh, 84.
Three others, including a policeman, remain in critical condition.
Chief Edwards said Lieutenant Brian Murphy, 51, had been tending to a victim at the scene when he was "ambushed" by the gunman.
The policeman was shot eight or nine times at "very close range", and was in critical condition on Monday.
The gunman also fired at a police car and ignored orders to drop his weapon, before he was shot dead outside by police, said the authorities.
Page used a 9mm semi-automatic pistol, which was recovered at the scene and had been bought legally, authorities said.
Edwards: Police officer was ambushed by shooter
Officials told reporters on Monday they were treating the case as possible domestic terrorism.
"We are looking into ties of white supremacist groups," FBI Special Agent in Charge Teresa Carlson said, but declined to specify details of their investigation.
Ms Carlson also said the FBI was looking for a "person of interest" at the scene who left before he could be questioned.
A civil rights group, the Southern Poverty Law Center, has described Page as a "frustrated neo-Nazi who had been the leader of a racist white-power band".
He left his native Colorado and joined a skinhead music group, End Apathy, in 2005, the civil rights organisation said.
On Sunday night, the authorities searched Page's house in the town of Cudahy, a few miles from the temple.
American Sikhs have reported being targeted since the 9/11 attacks, often because they are mistaken for Muslims as a result of wearing turbans and beards.
The Sikh Coalition has reported that there have been more than 700 incidents of harassment or assault against Sikhs in the US since the 9/11.
The Sikh Temple of Wisconsin was founded in 1997 and is said to have a congregation of about 400 worshippers.
"These are people I've grown up with," Gurpreet Kaur, 24, told the Associated Press. "They're like aunts and uncles to me. To see our community to go through something like this is numbing."
Sikh activists in India have protested over the shootings
Indian Prime Minister Manmohan Singh, who is himself a Sikh, spoke of his shock on Monday at the shooting.
"That this senseless act of violence should be targeted at a place of religious worship is particularly painful," Mr Singh said.
Dozens of Sikhs have protested over the shootings in the Indian cities of Delhi and Jammu.
Police in New York and Chicago said they had taken extra measures to monitor Sikh temples in those cities.
Wisconsin, which passed a law in 2011 allowing citizens to carry a concealed weapon, has some of the most permissive gun laws in the US.