Chula Vista Police arrested four students at Eastlake Middle School (EMS) after an "explosive device" was found on campus.
School Resource Officers (SRO's) from CVPD arrived on campus on Wednesday to find the explosive device already detonated, CVPD said.
San Diego Sheriff Bomb Squad responded and assisted with the investigation. The investigation revealed that several chemicals had been mixed together in a plastic soda bottle and then shaken to cause it to explode, CVPD said.
No students were harmed and no property was damaged from the detonation.
Police identified four male students as the suspects and they all admitted and cooperated with the investigation.
The students said they did not intend to cause harm, according to CVPD.
All four were arrested for possession of a destructive device and use of an explosive device, CVPD said.
EMS currently serves 1,700 students in grades 7 and 8.