BROKEN ARROW, Okla. (AP) — The deaths of eight people — including six children — found in a burning Oklahoma home are being investigated as a murder-suicide, with both adults considered suspects, authorities said Friday.

The children, who ranged in age from 1 to 13, were the victims, Broken Arrow Police Chief Brandon Berryhill said during a news conference. He did not provide their identities, ages or explain their relationships to one another. Police have not responded to calls and questions sent by email.

The causes of death are still under investigation but Broken Arrow Fire Department Chief Jeremy Moore said it doesn’t appear that anyone died because of the fire. Guns were recovered from the home, the police chief said.

“To arrive on scene yesterday and to see the looks on our first responders’ and firefighters’ faces just absolutely broke my heart,” Moore said Friday.

Sara Abel, a spokeswoman for the Bureau of Alcohol, Tobacco, Firearms and Explosives, said the agency is assisting local police in tracing guns found in the home but she did not have any details about the type or number of firearms.

The fire was reported about 4 p.m. Thursday in a quiet residential area of Broken Arrow, Oklahoma, 13 miles (20 kilometers) southeast of Tulsa.

Crews who responded found two adults dead in the front of the house with injuries that “appeared to be criminal in nature,” Moore said.

The children were found dead in another area of the home, he said.

A week ago, a similar tragedy occurred in Wisconsin, where four children and two adults were found in a burning apartment in a suspected murder-suicide.

In Broken Arrow, Catelin Powers said she was driving with her children nearby when she saw a column of smoke near her house, so she drove past to investigate.

“When I got closer to the house, I saw smoke pouring out from the very top of the house, which looked like maybe the attic,” she told The Associated Press on Thursday.

Two men and a woman on her phone were standing in front of the house, Powers said, when another man emerged from the front door dragging an apparently unconscious, unresponsive woman. “Her arms were flopped to her sides,” she said.

Suspecting the woman was dead, Powers said she drove on so her children would be spared the sight.

Tragedy has struck before in Broken Arrow, which is Tulsa’s biggest suburb with almost 115,000 residents. In 2015, two teenaged brothers killed their mother, father, two younger brothers and 5-year-old sister at their home — which was about 6 miles (10 kilometers) south of Thursday’s fatal fire.

The home where the 2015 killings occurred was later demolished and the site was transformed into a community park.