Authorities say a fired water plant worker is under arrest after he set his car on fire outside one plant and made a bomb threat against another.

West Palm Beach spokesman Elliot Cohen said during a news conference that 52-year-old Douglas Ellington drove his car to the city's water treatment plant Monday and set it on fire. Cohen says Ellington told firefighters the car contained a bomb, so they backed off. No bomb was found.

Cohen says Ellington also made a false bomb threat against the nearby Riviera Beach treatment plant.

He added that Ellington was fired from West Palm Beach in 2011 and from Riviera Beach this year, and has been arrested several times.

Jail records show he's been arrested three times since August for trespassing and failure to leave.