A late-night blaze at Chevron’s El Segundo refinery prompted emergency alerts, road closures, and shelter-in-place orders for nearby residents before crews brought the situation under control by Friday morning.

The fire broke out around 9:30 p.m. Thursday inside an isolation unit at the sprawling facility, according to Los Angeles County officials. By dawn, Chevron’s on-site fire department, using remote-operated water lines, had contained the flames and prevented the incident from spreading elsewhere within the refinery complex.

Authorities said no injuries occurred, and all employees and contractors were safely accounted for.

As a precaution, residents of Manhattan Beach were urged to remain indoors with doors and windows shut, and to keep pets inside until air quality risks were cleared.

El Segundo Mayor Chris Pimentel credited ongoing emergency preparedness drills with helping both city officials and Chevron staff respond swiftly. “We regularly train for these kinds of events — from oil spills to refinery fires — and that coordination paid off,” he said.

County Supervisor Holly Mitchell confirmed the fire’s suspected point of origin but noted that a full investigation into the cause remains underway.

The refinery, one of the largest on the West Coast, is a critical fuel supplier for Southern California. While officials said the fire was contained, it was not immediately clear whether operations at the site would be affected in the coming days.