Three people have been found dead inside a Mesa apartment and the case is being investigated as a murder-suicide, police said Tuesday.

Police said they received a call about a possible shooting around 7:30 p.m. Monday.

When officers arrived, they were directed by the caller to the apartment where he lived with his 46-year-old girlfriend and her 21-year-old son and 14-year-old daughter.

The man told police that he came home from work and found the bodies, each in a different room in the apartment.

Detectives said evidence at the scene appears to show that the 21-year-old fatally shot his mother and teenage sister and then killed himself.

Police said the names of the three people were being withheld pending notification of additional family members.