ANTIOCH, Calif. (AP) — A Northern California man has been arrested on suspicion of killing his girlfriend and 15-year-old son, authorities said Sunday.

The bodies of the teen and the 30-year-old woman were found Saturday night at an apartment in Antioch, east of San Francisco, after a neighbor requested a welfare check, police said in a statement.

“Both victims were suffered from obvious trauma and this incident was determined to be a homicide,” the statement said.

Police later arrested the suspect, a 34-year-old man, at a train station in Redwood City, south of San Francisco. He was not immediately identified.

Officials said the suspect was in a relationship with the woman and the teen was the suspect’s son.