Police say an explosion outside the Nellie Thornton High School in Mount Vernon sent four students to the hospital Friday.

Investigators say chemicals brought to the school by two students erupted in a garbage can at approximately 9:45 a.m.

"I was told by my administrator to search these kids," says school security guard David Clark. "I searched, and I found what happened to be something illegal."

According to Mount Vernon Police Commissioner David Chong, the teens brought a homemade device, similar to a stink bomb, but slightly stronger.

Students were evacuated after the blast and taken to a nearby church, where they remained for several hours before returning to school.No one was seriously injured, but four students, including the two who allegedly caused the explosion, were taken to Mount Vernon Hospital for precautionary observation.

Following the incident, the two teens were charged with reckless endangerment and illegal possession of noxious materials. Their case will be referred to family court.