The fire truck, Engine 309, was southbound on Flatbush Avenue, responding to a fire with lights and sirens activated.
It collided with the motorcyclist, who was westbound on Avenue U in front of Kings Plaza at 11:55 p.m. Sunday.
The motorcyclist was pronounced dead at Brookdale University Hospital. He was later identified as 30-year-old Valentin Ivancsuk.
The firefighters on the fire truck were checked out at the scene.
The FDNY says the "incident is under investigation."
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