Billings firefighters were held at bay by gunfire at a house fire Sunday that claimed the lives of multiple children and adults.

Police responding to a domestic incident heard gunfire and saw a man in the backyard of a house where smoke was visible. He suffered a self-inflicted gunshot wound and was pronounced dead at a local hospital, Billings Assistant Police Chief Shawn Mayo said at a press conference Monday.

Mayo would not say how many victims perished, adding that more information about the incident would likely be released Wednesday, according to The Billings Gazette.

Billings Fire Chief Matt Hoppel told the media: “Because the scene could not be immediately confirmed as secured, our firefighters were unable to operate as we normally would.” 

“The delay and limited access presented significant challenges. Fire conditions continued to worsen, and the residence ultimately became heavily involved and was consumed by fire.”

Water had to be shuttled to the incident as there are no hydrants in the subdivision.

Hoppel called it a very complex and dangerous incident for his firefighters who will be provided with mental health assistance. 

The Yellowstone County Sheriff's Office is leading the investigation.