AURORA, Colo. -- Aurora police are trying to determine who shot and killed a 21-year-old man early Tuesday morning and why.

Police officers were called to the victim's home, located in the 2000 block of South Vaughn Way, at about 1:50 a.m. Tuesday.

When officers arrived at the apartment, they saw that the man had been shot in the chest with a shotgun. He was transported to a local hospital, where he was pronounced dead at approximately 2:15 a.m.

His name is being withheld pending notification of family members.

Homicide detectives were called to the scene and learned that the victim had been out earlier in the evening with a friend, and when the two men returned to the apartment, they were arguing, police said.

The victim was eventually shot inside the apartment while the two men struggled over a shotgun, police said. The victim's roommate called the police to report the shooting.

Investigators are still trying to determine how the victim was shot.

The role of the victim's friend has not yet been determined.

At this time, detectives are not looking for any additional suspects in connection with this case. Anyone with information on the case is asked to contact Detective Gretchen Fronapfel at 303-739-6013.