A 21-year-old man was arrested and charged with first-degree murder after three people were found dead at a house in Aurora, Colorado.

Police responded to a welfare check call at a home in the 1500 block of South Evanston Street in the Willow Park neighborhood in Aurora on Saturday evening. Responding officers said they didn't find anything suspicious at the scene on arrival that would have suggested a forced entry, so eventually left the home, KKTV reported.

"Officers left the residence and notified family about their inability to force entry into the house," according to a press release by Aurora Police Department.

However, around two hours later, family members arrived at the residence and found two women and one man in an unresponsive state. After investigation, police revealed the three people had possible gunshot wounds and other injuries, and were declared dead. The three victims were relatives, an APD spokesperson said.

"They were found with possible gunshot wounds and other injuries and were pronounced deceased a short time later," the press release added. "All three will be identified by the Arapahoe County Coroner's Office after they are positively identified and their next of kin notified."

The accused Christopher Martinez, who was known to all three victims, was arrested early Sunday in connection with the killings. Sgt. Faith Goodrich said the suspect was a guest at the residence, according to Denver Post.

"There's no threat to the community and we don't believe anyone else was involved," she added.

"This senseless violence is inexplicable," Chief Art Acevedo said in the release. "Thanks to the efforts of our dedicated personnel, the suspect has been taken into custody and our community can breathe a collective sigh of relief. Our hearts go out to the family of the victims."

A search into the Arapahoe County court records didn't reveal any criminal history of Martinez.

It wasn't immediately clear when the incident took place. Cops continue to investigate the circumstances that led to the shooting.

Police have also asked anyone with information regarding the incident to call Metro Denver Crime Stoppers at 720.913.STOP (7867). "Tipsters could be eligible for a reward of up to $2,000 and may remain anonymous," officials said.

An ambulance leaves the parking lot of the King Soopers grocery store in Boulder, Colorado after reports of an active shooter on March 22, 2021.Police responded to an active shooter at a grocery store in the western US state of Colorado
Ambulance AFP / Jason Connolly