A Riverdale man and his mother were found slain last night, and police said they may have been killed after interrupting a burglary at the home they shared.

Police were called to 5403 Morton Pl. in the Beacon Heights neighborhood shortly after 7 p.m. by a neighbor who reported a possible prowler. When they arrived, police found a man, between 30 and 40, dead on the front steps.

Inside the man's home across the street at 5402 Morton Pl., police found the body of a woman, between 60 and 70. The man's son, who arrived just after the police, also shared the house, neighbors said.

Prince George's County police declined to identify the family pending notification of relatives.

Police said the brutality of the slayings obscured the cause of death and that autopsies are scheduled.

A neighbor said the family had lived in the working-class neighborhood for at least 10 years, but that they mostly kept to themselves.

The shattered, front storm door lay in the front yard of the family's single-story, red-brick house. At the house where the man's body was found, there were bloody handprints and splatters of blood on the front door.