A security guard at Thornwood High School in South Holland, Illinois died on Thursday after helping to break up a fight between two female students.

Authorities say 54-year old Richard Cowser was found unconscious by paramedics at the school after collapsing against the lockers. Cowser was taken to a local hospital and pronounced dead that afternoon. An investigation is pending, and police are interviewing the students who were fighting.

Cowser’s family says he was in good shape, and now officials are trying to determine whether he was hit during the fight or if the death was from natural causes.

“The security guards run over there, trying to break the fight up. He jumped in front of the girls and he just slowly passed out. He leaned over into the locker and passed out,” student witness Tyshon Boyd said.

Boyd captured video of the fight on his phone. Cowser’s autopsy results are expected later today.

Image: Thornwood High School