LOS ANGELES—An “environmental hazard” that prompted the evacuation of University of California—Los Angeles’s (UCLA) Molecular Sciences Building was caused by a student who accidentally created a by-product that exploded, police said Sept. 30.

Campus police and fire department units responded to the building just after noon Sept. 29 on reports of the initially unspecified hazard and evacuated the building out of an abundance of caution, according to a UCLA campus alert. Staff and students were advised by the university to avoid the building, but the rest of the campus remained open.

The Los Angeles Police Department (LAPD) reported Sept. 30 that the hazard was caused by a student at the university who “inadvertently created a by-product that destabilized and became energetic, resulting in a small detonation.”

LAPD bomb squad and hazmat units assessed the remaining material and disposed of it on the scene, police said.

No injuries were reported in the detonation and no property was damaged, according to the LAPD.