Seven people, including a gunman, were killed in a shooting at a Sikh temple near Milwaukee Sunday in what police say is being treated as an act of domestic terrorism.

Authorities including the FBI, the ATF, the Milwaukee County Sheriff's Department and Cudahy police are now searching a house in Cudahy, Wis., believed to be linked to the suspect, WITI's Brandon Cruz reports.

A source close to the case told Fox News that the suspect is a white male in his 40s who is a former military member.

Prior to starting the search at the 3700 block of Holmes Ave., police asked two blocks of residents to leave the area or remain indoors. FBI agents are there with an armored truck, a trailer and other vehicles. Other law enforcement officers are there too, along with a police dog.

Police were called Sunday morning to respond to the shooting at the Sikh Temple of Wisconsin in the suburb of Oak Creek, when witnesses said several dozen people were gathering for a service.

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Sunny Singh, 21, of Milwaukee, said a friend pulled into the temple's parking lot, heard shots and saw two people fall down. The friend then saw the shooter reload his weapons and head to the temple's entrance, Singh said.

Oak Creek Police Chief John Edwards said the shooting suspect ambushed and opened fire on an 20-year veteran officer who was attending to a victim at the scene. Another officer then shot and killed the suspect.

Greenfield Police Chief Bradley Wentlandt said the officer who was ambushed was shot multiple times and is being treated in surgery, but is expected to recover.

Four people were found dead inside the temple, Wentlandt said, while three, including the suspected shooter, were found dead outside. Tactical units went through the temple and authorities do not believe a second shooter was involved, Wentlandt said. All people have been cleared out of the temple.

At a news conference late Sunday afternoon, Edwards released no information about the suspect, including his identity or a possible motive.

But at the scene of the home search, Kurt Weins, a Cudahy resident, told the Journal Sentinel he rented out the upper flat of the duplex to a man in his 40s.

"I had him checked out and he definitely checked out," Weins told the newspaper. "The cops told me they don't want me to say nothing right now."

Authorities were using a bucket truck to peek into the windows of the property Sunday evening.

Edwards said the FBI will lead the investigation because the shootings are being treated as an act of domestic terrorism.

Three other shooting victims, all men, were taken in critical condition to Froederdt Hospital in Milwaukee, the main trauma center for the area, Chief Medical Officer Lee Biblo said. He added that they were all being treated for bullet wounds: one to the chest, one to the extremities and the face and one to the neck.

Police released few details about other victims, but family members talked about discussions with some of those inside.

Sukhwindar Nagra, of Racine, said he called his brother-in-law's phone and a priest at the temple answered and told him that his brother-in-law had been shot, along with three priests.

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 and started firing. Kaur said her mother felt two bullets fly by her as the group fled to the pantry. Her mother suffered what Kaur thought was shrapnel wound in her foot.

A White House official said President Obama was notified of the shooting and is continuing to receive updates.

"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," Obama said in a statement.

Wisconsin Gov. Scott Walker also canceled a Monday event in Green Bay after hearing about the shooting.

"Our hearts go out to the victims and their families, as we all struggle to comprehend the evil that begets this terrible violence," he said in a statement. "At the same time, we are filled with gratitude for our first responders, who show bravery and selflessness as they put aside their own safety to protect our neighbors and friends."

County Alderman Dan Jakupczyk told Fox News that the people at the temple have been "good citizens."

“Since I’ve been alderman, for about three years, there has never been any trouble, or any problems,” he said.

One of the temple's committee members, Ven Boba Ri, told the Journal Sentinel that the shooting was very sad, and he has been fielding calls all morning from around the world, including India.

"Sikhism is such a peaceful religion. We have suffered for generations, in India and even here."

The NYPD also announced, out of caution, a heightened police presence at Sikh temples in New York City.

Sikhism is a monotheistic faith that was founded in South Asia more than 500 years ago. 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 U.S., according to estimates. The majority worldwide live in India.

Oak Creek is south of Milwaukee along Lake Michigan.

Fox News' Mike Levine and the Associated Press contributed to this report.

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