Police ordered residents in Antioch to stay indoors Monday after a man's body was found near Live Oak High School.
The order called for residents on F Street between West 11th to West 17th streets to shelter in place while police investigated.
Classes at nearby Live Oak High School and Antioch Middle School were canceled due to the police activity.
The Walnut Creek Police Department's bomb squad also responded to the scene.
Antioch Police Department Strategic Communications Officer Darryl Saffold said wires were found near the body of a man in his mid-50s. The man had suffered "severe trauma," though it wasn't clear how he died.
Investigators believe the man's injuries appeared to be self-inflicted.
Bay City News contributed to this report.