Twain Elementary School from its northeast corner. (File photo)

Two school custodians were fatally shot Monday afternoon at Mark Twain Elementary School in the Garfield Ridge neighborhood in an apparent murder-suicide, police said. 

Police said the shooting took place at 3:40 p.m. inside the school building at 5134 S. Lotus Ave. No children were present inside the school. Classes are scheduled to start in two weeks. 

Chicago police said the victims were a 48-year-old woman who suffered a single gunshot wound in the head and a 63-year-old man who was shot once in the head. Their identities were not immediately available. 

Both victims were taken to Advocate Christ Medical Center in Oak Lawn where they died. 

A weapon was found at the scene. 

Police reportedly said the man’s wound was apparently self-inflicted. 

Both victims were members of SEIU Local 73 union. 

The school principal informed Mark Twain families that shots had been fired inside the building and that CPS and CPD were responding. 

Detectives are investigating.