SACRAMENTO, Calif. (KRON) – Five people have been killed in a shooting at a Sacramento church on Monday night, according to the Sacramento Sheriff’s Office.

Authorities say a father killed his three kids under the age of 15, one other adult, and then himself.

According to officials, the shooter was estranged from the kids’ mother and had a restraining order against him.

Investigators say this occurred during a supervised visit with the children and the fourth victim was a chaperone, Sacramento County Sheriff Scott Jones said.

A church employee heard the gunshots and called 911, Sgt. Rod Grassmann with the Sacramento County Sheriff’s Office said. The shooting occurred in the main sanctuary area, he said.

A large police presence responded to 2041 Wyda Way. Around 6:09 p.m., authorities reported the police activity near Howe and Ethan, and Howe and Cottage.

Sheriff’s officials are investigating it as a domestic violence incident, Grassman said.

Officials didn’t know if the family members belonged to the church, which sits on a mostly residential block near a commercial area east of downtown Sacramento.

It wasn’t immediately known how many people were at the church or if there were any services or activities at the time of the shooting.

Residents are asked to avoid the area.

The Mayor Pro Tem of Sacramento Eric Guerra posted to Twitter that police are responding to a mass casualty at a church:

🚨Please be aware and on the look out. Local law enforcement are responding to a mass casualty shooting event in the county at a church on 2041 Wyda way. Please be alert while in the area as local law enforcement responds. 🚨

The governor’s office posted to Twitter saying:

We are actively monitoring the shooting at a church in Sacramento and working closely with local law enforcement. Our thoughts are with the community, parishioners, and all those impacted by this horrific event.

Photos on social media show armored trucks and a heavy police presence.

No other details have been released at this time.

The Associated Press contributed to this report.

Check back for updates as KRON4 learns more.