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The Big West of California refinery leaked a small amount of ammonia early Sunday that sounded an alarm in which a recorded voice told people to evacuate the area.

Emergency crews responded and no one was injured.

The alarm was meant to alert refinery personnel but was heard by an off-duty Bakersfield Police lieutenant at his home near Truxtun Avenue Extension and Coffee Road, according to police. Refinery personnel also heard the alarm and notified emergency responders shortly after it went off around 12:15 a.m. Sunday.

Refinery Health, Safety and Environment director Bill Chadick said the leak was very small and caused by a faulty valve on an ammonia storage tank.

Chadick did not know the quantity of ammonia released from the tank but said no one was injured or impacted in the incident.

“We have alarms in the ammonia area that are set to go off whenever they get even the slightest whiff of ammonia,” Chadick said. “The alarm went off and that's exactly what it's supposed to do.”

While ammonia diluted with water is typical for household uses, anhydrous ammonia -- which contains no water -- can be hazardous in the event of a sizable leak. Because the chemical has an extremely low boiling point, it will instantly vaporize, creating a cloud that can travel downwind. Exposure results in severe chemical burns.

The chemical is commonly used in industry and small leaks have occurred in Kern County on occasion, said county Environmental Health Services Director Matt Constantine, whose office continues to investigate the Big West leak.

"We  want to clearly understand why they had the release and is there some preventative maintenance that should have been performed," Constantine said.