A Long Island firefighter has been busted for setting off a string of blazes, including one started with a Molotov cocktail, authorities said Monday.

Christopher Cordeiro, a 20-year-old member of the Bethpage Fire Department, was arrested Sunday evening at the firehouse after allegedly setting a shed ablaze on North Hermann Avenue earlier that day.

An arson bomb squad investigation found he set off a Molotov cocktail made from a Corona Beer bottle in a pit last June and sparked a dumpster fire in March, officials said.

Cordeiro is also accused of setting fire to a wooded area Aug. 10 and an abandoned house Aug. 5.

The alleged pyromaniac started most of his blazes with piles of newspaper doused in accelerant, per court papers — though in one instance he’s accused of just setting the side of an empty building alight with an open flame.

Cordeiro was arraigned Monday in First District Court in Hempstead on charges of arson and criminal possession of a weapon, and a judge ordered him held on $75,000 bond.

Additional reporting by Emily Saul