MARTINEZ (CBS SF) – A fire in the boiler room of the county hospital in Martinez Friday afternoon forced some evacuations before being brought under control, according to authorities.

Fire officials said about the two-alarm fire started at the Contra Costa County – Martinez Health Center located at 2500 Alhambra Avenue shortly after 2 p.m. Officials said the fire started in the back of the hospital near the emergency room.

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A fire marshal with the Contra Costa County Fire Protection District later determined that the fire started in the boiler room.

The Contra Costa County Fire Protection District Twitter account posted that the fire was under control at about 2:53 p.m.

The smoke and fire forced personnel to clear the first two floors of the five-story hospital. The evacuation order was lifted shortly before 5 p.m.

Firefighters found the fire was fueled by one of two fuel sources, either natural gas or diesel fuel.

Firefighters haven’t pinpointed which fuel was burning, fire Marshal Robert Marshall said.

The hospital can run on both fuels in case one source is cut off for some reason such as a natural disaster.

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The damage to the boiler room was minimal. The cause is under investigation.