NEW YORK — An on-duty FDNY lieutenant was found dead inside a firehouse on Staten Island on Sunday, the department said.

FDNY Lieutenant Joseph Maiello, who was assigned to Ladder 83 on Jewett Avenue, was found unconscious inside the firehouse Sunday morning, according to the department.

Maiello, 53, was pronounced dead at the scene, the FDNY said. The city's Medical Examiner will determine how he died.

The Uniformed Firefighters Association confirmed Maiello’s death on Twitter Sunday afternoon. The lieutenant served with the FDNY for 22 years, the department said.

“Joe was an active member of the department who was working when he passed away in quarters, during his tour,” the union tweeted. “The UFA sends their deepest condolences to his wife and two children.”