At least seven people were killed and three wounded Sunday in a mass shooting at a Sikh temple on the outskirts of Milwaukee, Wisconsin, police said.

Greenfield police chief Bradley Wentlandt confirmed that four people had been found dead inside the temple and three outside, one of whom was the gunman, who apparently acted alone.

Wentlandt said that a police unit was dispatched to the Sikh temple in Oak Creek, a Milwaukee suburb, after several 911 calls were received reporting shots fired at 10:25 a.m. local time (1525 GMT).

Oak Creek police chief John Edwards said that one of his officers who responded to the scene was treating a victim when he was "ambushed" by the gunman in the parking lot. The officer was shot multiple times and rushed to Milwaukee's Froedtert Hospital where he underwent surgery, he added.

The suspected mass murderer - who was not identified - was almost immediately shot and killed by a second officer, police said.

Later, authorities found four bodies inside the temple and two more outside, besides the gunman.

At present, the motives for the attack are not known, but U.S. authorities said that it was being treated as an act of "domestic terrorism."

Dozens of worshipers, among them many women and children, were gathering for a meal before the 11:30 a.m. prayer service at the temple when the shooting occurred. Approximately 500 members are in the temple's congregation, officials said.

The chief medical officer of Froedterdt Hospital, Lee Biblo, said that the health center had admitted three wounded men in the wake of the shooting, all of whom are in "critical" condition with multiple gunshot wounds.

Wisconsin's Republican governor, Scott Walker, said in a communique that local authorities are working with the FBI to uncover the facts in the case.

President Barack Obama sent his condolences to the Sikh community, and presumptive Republican presidential nominee Mitt Romney did the same.

The Sikh religion, which is the fifth largest in the world in terms of numbers of believers with 27 million, is a monotheistic faith that sprang up in India in the 16th century. As many as 500,000 Sikhs live in the United States.

More than 700 hate-related incidents against Sikhs have been reported since the Sept. 11, 2001, terror attacks, according to the Associated Press. "Sikhs don't practice the same religion as Muslims," the AP noted, "but their long beards and turbans often cause them to be mistaken for Muslims, advocates say." EFE