Late Sunday, the investigation appeared to move beyond the temple as police, federal agents, and the county sheriff's bomb squad swarmed a neighborhood in nearby Cudahy and evacuated several homes. Police roped off four blocks around a duplex, but the building's owner, Kurt Weins, said authorities would not say why they were there or whether it was related to the shooting.
Oak Creek Police Chief John Edwards said police expected to release more information Monday. He said the FBI would lead the investigation because the shootings were being treated as domestic terrorism, or an attack that originated inside the United States.
"While the FBI is investigating whether this matter might be an act of domestic terrorism, no motive has been determined at this time," Teresa Carlson, special agent in charge with the agency's Milwaukee division, said in a statement Sunday night.
During a chaotic few hours after the first shots were fired around 10:30 a.m. local time, police in tactical gear and carrying assault rifles surrounded the Sikh Temple of Wisconsin with armored vehicles and ambulances. Witnesses struggled with unrealized fears that several gunmen were holding women and children hostage inside.
Jatinder Mangat, 38, of Racine, said his uncle Satwant Singh Kaleka, the temple's president, was one of those shot at the temple, but he didn't know the extent of Kaleka's injuries. When he later learned that people had died, Mangat said "it was like the heart just sat down."
One of the first officers to respond to frantic 911 calls was shot several times as he tended to a wounded victim, and he was in critical condition along with two other victims Sunday night, authorities said.
Edwards said the gunman "ambushed" the officer, a 20-year veteran with tactical experience. A second officer then exchanged gunfire with the attacker, who was fatally shot. Police had earlier said the officer who was shot killed the gunman.
Tactical units went through the temple and found four people dead inside and two outside, in addition to the shooter.
The three wounded were being treated at a trauma center. Greenfield Police Chief Bradley Wentlandt, who assisted the investigation, said the police officer had surgery and was expected to survive.
Gurpreet Kaur, 24, of Oak Creek, said her mother and a group of about 14 other women were preparing a meal in the temple kitchen when the gunman entered. Kaur said her mother felt two bullets fly by her as the group fled to the pantry. Her mother suffered what Kaur thought was a shrapnel wound in a foot.
"These are people I've grown up with," she said. "They're like aunts and uncles to me. To see our community to go through something like this is numbing."
Many Sikhs in the United States worship on Sundays at a temple, or gurdwara, and a typical service consists of meditation and singing in a prayer room where worshipers remove their shoes and sit on the floor. Worshipers gather afterward for a meal that is open to community members, regardless of their religious beliefs.
Kaur said she spent the afternoon serving as a translator between law enforcement and survivors at a bowling alley. Police investigators kept witnesses in the bowling alley basement into the evening.
Sikhism is a monotheistic faith founded more than 500 years ago in South Asia. It has roughly 27 million followers worldwide. Observant Sikhs do not cut their hair; male followers often cover their heads with turbans - which are considered sacred - and refrain from shaving their beards. There are roughly 500,000 Sikhs in the United States, according to estimates. The majority worldwide live in India.
The Sikh Temple of Wisconsin started in 1997 with about 25 families who gathered in community halls in Milwaukee. Construction on the current temple in Oak Creek began in 2006, according to the temple's website.
Sikh rights groups have reported a rise in bias attacks since 9/11. The Sikh Coalition in Washington has reported more than 700 incidents in the United States since 9/11, which advocates have blamed on anti-Islamic sentiment. Sikhs are not Muslims, but their long beards and turbans often cause them to be mistaken for Muslims, advocates say.
Police in New York and Chicago issued statements saying they were giving Sikh temples in those cities additional attention as a precaution after the shooting, which happened two weeks after a gunman killed 12 people at movie theater in Colorado.
Valarie Kaur, who chronicled violence against Sikh Americans in the 2006 documentary Divided We Fall, was returning to her home in New Haven, Conn., after speaking at a White House conference Friday when she heard about the shootings.
Even though the gunman's motives were a mystery Sunday, Kaur said the shootings reopened wounds in a community whose members have found themselves frequent targets of hate-based attacks since 9/11.
"We are experiencing it as a hate crime," she said. "Every Sikh American today is hurting, grieving, and afraid."