Five people were hurt in a two-alarm blaze on the Upper East Side this morning, authorities said.

Three firefighters and two civilians were injured in the fire that began in the basement of a five-story building on East 88th Street, near York Avenue, at about 5:30 a.m., according to an FDNY spokesman.

The flames spread up to the roof through the building shaft, and damaged the first, second and fifth floors, the spokesman said.

Over a hundred firefighters worked to extinguish the blaze by 7:30 a.m., authorities said.

One firefighter was listed in serious condition at New York Presbyterian Hospital, and the others were taken there in stable condition, the spokesman said.

Fire marshals are investigating what sparked the flames.