Three firefighters were injured Sunday morning when a fire started on a utility pole in Bay Shore, possibly in a transformer, and spread to a car and then two trailers nearby.

According to a preliminary report from Suffolk County police, the incident occurred about 10:45 a.m. on Cleveland Avenue and “explosions” could be heard from small propane tanks on one of the trailers.

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The report said three Brentwood firefighters were hurt, but not seriously.

Suffolk County arson investigators have determined the fire to be accidental but they remained at the scene doing a further probe Sunday afternoon.

No other information was immediately available.