Police said a 33-year-old man is believed to have fatally shot three family members before killing himself.
THORNTON, CO — Four people were found dead inside a Thornton home Friday night after a family member reported several people unresponsive, and police are investigating the deaths as an apparent murder-suicide.
The case centers on a home in the 13900 block of Harrison Street, where officers arrived just after 8 p.m. May 22. Thornton police said the dead included two men, a woman and a juvenile, all with apparent gunshot wounds. Investigators said one adult male, age 33, is believed to have killed the other three family members before dying by suicide. Authorities have not released the names of those who died.
Police said the first call came from a family member who believed multiple people inside the home were unresponsive. Officers entered the residence and found four people who were “obviously deceased,” according to the department’s account of the response. The department later said detectives believed the deaths happened that evening. “The entire Thornton Police Department is deeply saddened by this tragedy and extends its condolences to the family and loved ones of everyone involved,” a police spokesperson said.
The department initially described the case as a homicide investigation. Later updates said detectives believed the 33-year-old man shot the three others and then himself. Police said there was no known threat to the public, a statement that pointed to an isolated case rather than a search for an outside suspect. The Adams County Coroner’s Office is responsible for confirming the identities of the four people and making formal death rulings after autopsies and family notifications.
Authorities have not released the relationship between each person in the home beyond saying they were family members. They also have not released a possible motive, the type of firearm used or whether officers had been called to the address before Friday night. The home sits in a residential part of Thornton, a city north of Denver that spans parts of Adams and Weld counties. The 13900 block of Harrison Street remained the focus of the investigation as detectives gathered evidence and reviewed what happened before the call to police.
The next steps belong to Thornton detectives and the Adams County Coroner’s Office. Detectives are expected to complete interviews, process evidence from the home and determine a fuller timeline of the shootings. The coroner’s office will identify the dead once positive identification is complete and relatives have been notified. Because the person believed responsible is dead, police did not announce pending arrests or charges. The case remained open as investigators worked to close gaps in the timeline.
Police acknowledged the effect of the deaths on neighbors and the wider community. “We recognize that incidents like this are difficult for neighbors and our entire community,” the department spokesperson said. Officers said the department’s Victim Services Unit and Co-Responder Team were available to assist people affected by the case. Investigators also asked anyone with information to contact the Thornton Police Department tip line at 720-977-5069.
As of Sunday, May 24, the victims had not been publicly identified, and police had not released a motive. The next major update is expected after the Adams County Coroner’s Office confirms the identities and causes and manners of death.
Author note: Last updated Sunday, May 24, 2026.