PHILADELPHIA (AP) — Police say a man is in custody following the deaths of his mother, stepfather and two brothers, including a 6-year-old boy, who were found shot in a west Philadelphia home.

Officials said in a statement that officers were sent Wednesday afternoon to check on a couple who didn’t show up for work and were “known to have trouble with a mentally unstable son.”

Arriving officers found a 29-year-old man in a second-floor bedroom and took him into custody. His 51-year-old mother was found shot by the front door and his stepfather was found by the basement door, while a 17-year-old brother was found shot in a second-floor bedroom and a 6-year-old brother was found shot in the kitchen.

All four victims were pronounced dead at the scene and a weapon was recovered.