The 53-year-old was discovered unconscious while on duty at his fire house, Engine 163 and Ladder 83 on Staten Island, on Sunday.
Maiello was a 22-year veteran of the fire department.
FDNY Commissioner Daniel Nigro paid his respects to Maiello at Mathew Funeral Home on Victory Boulevard.
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He said today was a sad day for the fire department and for the Maiello's family.
Nigro says Maiello's sudden death hit everyone he works with very hard.
"Death at this time of year seems even more difficult to take as we try to enjoy this holiday season together. We certainly can't now," Nigro said. "Tomorrow he'll be given a real department sendoff that he so deserves."
Maiello's funeral will be held Thursday morning at Holy Family Roman Catholic Church on Staten Island.
He's survived by his wife and two children.
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