PLYMOUTH, Mass. (AP) -- A custodian was found dead Monday at a Massachusetts elementary school and several public safety employees who responded to the scene developed symptoms of possible chemical exposure, police and prosecutors said. The man who was found unresponsive around 8:15 a.m. was identified by the district attorney's office as 53-year-old Chester Flattery, the custodian for Manomet Elementary School. Three firefighters, three police officers, two state troopers, two paramedics and a school employee were taken to a hospital for evaluation with symptoms of possible exposure, according to the statement from police and prosecutors. Fire officials said earlier in the day that most had been treated for minor symptoms of eye and throat irritation and released. The building was evacuated, and officials said a hazardous materials team was attempting to identify the chemical agent. An autopsy was planned for Flattery by the office of the chief medical examiner. The death was under investigation by the Plymouth police department, Massachusetts state police detectives and the office of the state fire marshal.