A discarded cigarette caused the fiery car explosion that injured seven firefighters in the Bronx this week, FDNY officials said.

Department Chief John Esposito said the “careless disposal of a lit cigarette” started a trash fire on Fox Street near Westchester Avenue in Longwood around 7 p.m. Wednesday. The blaze quickly spread to a car parked nearby, igniting its gas tank and triggering the explosion, he said.

Of the seven firefighters injured, five were treated for serious burns to their faces and arms and three were admitted to Jacobi Hospital, according to officials. All the firefighters were expected to recover fully, Esposito said.

“If you’re smoking, don’t flick your cigarette butts,” he said in a video message Thursday. “We remind all New Yorkers to properly extinguish cigar

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