Authorities say 'intentional detonation' triggered explosion at California medical building
© Getty Images

An explosion at a medical building in Orange County, Calif., on Tuesday was caused by an “intentional detonation,” federal investigators told NBC Los Angeles.

One person died and at least three were injured after the explosion at the Aliso Viejo medical building. The explosion led children at a nearby day care to flee and a bomb squad was at the scene, authorities told NBC.

Bomb squad investigators and FBI agents are looking into what caused the blast but authorities said there was no lingering threat, according to NBC.

ADVERTISEMENT

A fire that broke out in the building, which was under construction, was put out by crews, NBC reported.

Initial reports of the explosion claimed a car crashed into the building around 1 p.m. and that the explosion was not considered suspicious.

However, Orange County Sheriff's Department spokeswoman Carrie Braun said no car was involved in the explosion and there is an investigation to find out what caused it, according to NBC.