The gunman, identified by co-workers as Steve Leith, a science teacher, was arrested at Chelsea High School, the police said. The shooting occurred about an hour after classes ended, during a staff meeting. The Police Chief, Lenard McDougall, said of the suspect: "I found him sitting in a chair in the classroom by himself. He said 'Hi,' and he was taken into custody. He was quiet, very quiet." A 9-millimeter semiautomatic gun was found outside the building, the police said. Joseph Piasecki, superintendent of Chelsea schools, died at Chelsea Community Hospital of multiple gunshot wounds. Phil Jones, 44, an English teacher, was treated for a stomach wound. The principal, Ronald Mead, 43, was shot in the leg.