A Denver couple returned to their apartment early Sunday morning to find an intruder inside, according to Denver police. The man who lived there shot the intruder several times, killing him.

The shooting was first reported around 1 a.m. in the 2300 block of East Evans Avenue, just west of South University Boulevard near the University of Denver.

A police presence was seen at the One Observatory Park building at 2360 East Evans Avenue.

The couple was “surprised” by the man in their apartment, police said.

Few other details were immediately available but police say the resident who shot the intruder is cooperating with the investigation.

Colorado law allows someone to use deadly force to protect themselves or others from death, serious injury, sexual assault or kidnapping.

Zach Lyons, a resident in the building, got home around 8:30 or 9 a.m. after staying the night at his girlfriend’s house. He arrived to see police cars all over the place.

“It’s definitely pretty alarming,” he said. “I wasn’t here last night, I don’t have any first-hand accounts or anything but it’s definitely alarming to know something like this happened in your own community right down the hall.”

He described the apartment as “not cheap” but “a nice place to live,” and “fairly vacant right now with it being right across from DU.”

It’s scary,” he said. “I guess it would have been fortunate if it happened to me since I wasn’t home and it’s just property, but it’s definitely concerning, knowing there was a break-in down the hall and it resulted in a loss of life.”

He said he hasn’t heard anything from Denver police aside from its tweets and hasn’t heard anything from the building’s management.

CBS News Colorado reached out to the management company Sunday morning and has not yet heard back.

Another neighbor said he heard about five gunshots. He described the building as “fairly secure,” but said “there are definitely some weak points.” He described the neighborhood as safe too, and didn’t realize the gunshots came from inside the building. 

Police have not said whether the intruder was a resident of the building.

That neighbor also said he hasn’t heard anything from the building’s management company, something he hopes changes soon.