A relative found signs of trouble at the Harrison Street home Friday night.
THORNTON, Colo. — Thornton police are investigating the deaths of four people found inside a home Friday night as an apparent family murder-suicide, officials said.
The deaths were reported in the 13900 block of Harrison Street after a family member contacted police about people who appeared to be unresponsive inside the residence. Officers arrived shortly after 8 p.m. and found four people dead.
Police said the dead included two adult men, one woman and one juvenile. Detectives believe a 33-year-old man fatally shot three family members before dying by suicide. Authorities have not publicly identified the man or the other three people.
The Adams County Coroner’s Office will confirm the identities and determine official causes and manners of death. Police have described the wounds as apparent gunshot wounds but have not released details about the weapon, the exact time of the shooting or a possible motive.
Thornton police said there was no known danger to the community. Detectives continued working through the home and nearby area Saturday, gathering evidence and reviewing what happened before officers were called.
The department said the case has shaken people beyond the home. “We recognize that incidents like this are difficult for neighbors and our entire community,” a Thornton police spokesperson said.
No arrests were expected because investigators believe the suspected shooter died at the scene. Police said the next public updates are expected after the coroner’s office completes identification and relatives are notified.
Author note: Last updated May 24, 2026.