OAK CREEK, Wis. — The priests had gathered in the lobby of the sprawling Sikh temple here in suburban Milwaukee, and lunch was being prepared as congregants were arriving for Sunday services.
Instead of worshipers, though, an armed man stepped through the door and started firing.
In an attack that the police said they were treating as "a domestic terrorist-type incident," the gunman stalked through the temple around 10:30 a.m. Congregants ran for shelter and barricaded themselves in bathrooms and prayer halls, where they made desperate phone calls and sent anguished texts pleading for help as confusion and fear took hold. Witnesses described a scene of chaos and carnage.
Jatinder Mangat, 40, who was on his way to the temple when he heard reports about the shooting, said he had tried to call his uncle, the temple's president, but reached the head priest, Gurmail Singh, instead. "He was crying. Everyone was screaming," Mr. Mangat said. "He said that my uncle was shot and was lying on the floor and asked why you guys are not sending an ambulance and police."
Mr. Singh, he said, had locked himself in a bathroom with four other people, including two children.
Six people were killed and three others were wounded on Sunday at the 17,000-square-foot Sikh Temple of Wisconsin in Oak Creek, a city of about 35,000 just south of Milwaukee, officials said.
The gunman's rampage ended when one of the first police officers to arrive shot and killed him. Another police officer, who tried to aid a victim, was ambushed by the gunman and shot multiple times. He was in critical condition but was expected to survive, the authorities said.
The police did not release any details about the gunman or a possible motive for the shooting, beyond raising the prospect of terrorism. Thomas Ahern, a spokesman for the Bureau of Alcohol, Tobacco, Firearms and Explosives, said the killer was a 40-year-old white man.
John Edwards, the police chief in Oak Creek, said at a news conference that weapons had been found at the scene. He said the F.B.I. would lead the investigation.
"This remains an active investigation in its early stages," Teresa Carlson, the special agent in charge of the F.B.I.'s Milwaukee division, said in a statement. "While the F.B.I. is investigating whether this matter might be an act of domestic terrorism, no motive has been determined at this time."
The shootings reverberated from this small community to Washington and beyond, including India, where the religion was founded and many of the congregants have family ties.
President Obama and his Republican challenger, Mitt Romney, released statements on Sunday expressing sorrow.
"Michelle and I were deeply saddened to learn of the shooting that tragically took so many lives in Wisconsin," the president said. "At this difficult time, the people of Oak Creek must know that the American people have them in our thoughts and prayers, and our hearts go out to the families and friends of those who were killed and wounded."
Mr. Romney called the shootings "a senseless act of violence and a tragedy" that he said should never befall any house of worship.
"Our hearts are with the victims, their families and the entire Oak Creek Sikh community," Mr. Romney said. "We join Americans everywhere in mourning those who lost their lives and in prayer for healing in the difficult days ahead."
Many members of the close-knit Sikh community here said the attack had shattered their sense of security.
"Everyone here is thinking this is a hate crime for sure," said Manjit Singh, who goes to a different temple in the region. "People think we are Muslims."
Though violence against Sikhs in Wisconsin was unheard of before the shooting, many in this community said they had sensed a rise in antipathy since the attacks on Sept. 11 and suspected it was because people mistake them for Muslims. Followers of Sikhism, or Gurmat, a monotheistic faith founded in the 15th century in South Asia, typically do not cut their hair, and men often wear colorful turbans and refrain from cutting their beards.
"Most people are so ignorant they don't know the difference between religions," said Ravi Chawla, 65, a businesswoman who moved to the region from Pakistan in the 1970s. "Just because they see the turban they think you're Taliban."
There are around 314,000 Sikhs in the United States, according to the Association of Religion Data Archives. The temple in Oak Creek, one of two large congregations in the Milwaukee area, was founded in 1997 and has about 400 worshipers.
Threats against Sikh-Americans have become acute enough that in April, Representative Joseph Crowley, Democrat of New York and co-chairman of the Congressional Caucus on Indians and Indian-Americans, sent a letter to Attorney General Eric H. Holder Jr. urging the F.B.I. to collect data on hate crimes committed against them. In the previous year alone, he said in the letter, two Sikh men in Sacramento were slain, a Sikh temple in Michigan was vandalized, and a Sikh man was beaten in New York.
"The more information our law enforcement agencies have on violence against Sikh-Americans, the more they can do to help prevent these crimes and bring those who commit them to justice," Mr. Crowley said in a statement at the time.
By Sunday evening, the F.B.I. had cordoned off a street in Cudahy, a town about five miles from the temple, where it was executing a search warrant related to the shooting, Ms. Carlson said at a news conference. "It's going to be a long night," she said, declining to give further details. A law enforcement official said some residents on the street had been ordered to leave their homes.
At a news conference, Chief Edwards described a dramatic scene when officers arrived at the temple soon after the first 911 call. After the gunman ambushed the first officer, Chief Edwards said, another police officer exchanged fire with the gunman, bringing him down.
Bradley Wentlandt, the chief of police in nearby Greenfield, said the wounded officer was a 20-year veteran whose actions probably saved many lives.
Four bodies were found inside the temple and three outside, including that of the gunman, Chief Wentlandt said.
Three men with gunshot wounds were admitted to Froedtert Hospital, the Milwaukee region's main trauma center, said Nalissa Wienke, a spokeswoman for the hospital. One victim had been shot in the head and extremities and another in the abdomen. The third was described as having neck wounds.
There were initially conflicting reports about whether there was more than one gunman and whether hostages had been taken inside the temple. Local news agencies, citing text messages from people inside, reported that two or more gunmen could have been involved.
"The best information is that there was only one gunman," Chief Edwards said at a news conference.
The shooting came about two weeks after a gunman killed 12 people and wounded nearly 60 in an attack at a movie theater in Aurora, Colo.
In response to the shooting on Sunday, the police in New York said security was being increased at Sikh temples in the city. "There is no known threat against Sikh temples in New York City; however, the coverage is being put in place out of an abundance of caution," the New York police said in a statement.
Outside the temple here, friends and relatives were struggling to understand what had happened. Many in the community had contacted friends and family who were in the temple when the violence broke out.
Harpreet Singh, a nephew of the temple president, said his aunt, the president's wife, was in the kitchen with other women preparing food for services when they heard gunshots.
"She said they heard a bang, bang, bang," Mr. Singh, 36, said in a telephone interview from the basement of a bowling alley near from the temple, where the police and F.B.I. agents were interviewing survivors.
Mr. Singh, recounting the shooting as told to him by his aunt Satpal Kaleka, said the women had hidden in a nearby pantry. The women escaped, witnessing the gunman's carnage along the way, he said.
Mr. Singh was on his way to services with his wife, his two children and his parents when the police stopped them outside the parking lot. "There were police cars running into the complex," he said. "A couple of weeks ago, some kid had set off a fire alarm, so we thought something like that had happened."
People begin gathering at the temple as early as 6:30 a.m. on Sundays, but most arrive around 10:30 or 11 for services, Mr. Singh said. He believed about 30 to 35 people were inside when the shooting began, but had the gunman arrived just 15 minutes later, Mr. Singh said, 100 to 150 people would have been inside.