A gunman, who opened fire Sunday, at the Sikh Temple of Wisconsin in Oak Creek, was fatally shot after killing at least six people.

The shooting began during the temple’s Sunday morning services, when the building was crowded with men, women, and children, according to the New York Times.

The gunman was killed after he ambushed one of the officers helping a victim. Another officer then shot the gunman multiple times, reported the Milwaukee Journal Sentinel.

Police officers were dispatched to Sikh temples in Brookfield and Waukesha County as a precaution following the shooting in Oak Creek.

Although police did not release any information regarding the shooter or a possible motive, a briefing will be held Monday morning at 10 a.m.

The F.B.I. will lead further investigation of the shooting, treating the attack as an act of domestic terrorism, according to John Edwards, the police chief of Oak Creek.