Little Liam Witt died Jan. 24 after enduring years of radiation and chemotherapy.
The firefighters of Ladder Co. 24 and Engine Co. 1 admired Liam's fighting spirit. They gave him his own locker in their midtown Manhattan firehouse.
Dozens of firefighters attended Monday's service at the nearby St. Francis of Assisi Church. Bagpipers played. Speakers included a doctor and a nurse from Memorial Sloan-Kettering Cancer Center who treated Liam.
Mementos from Liam's life on display at the church included his scooter and a Curious George book.