At least 10 firefighters were injured while battling a blaze early Sunday morning in a mostly vacant commercial building in Midtown Manhattan.

The injured firefighters were were hospitalized for issues related to heat exhaustion and smoke inhalation, according to news media reports. There were no civilian injuries, the FDNY said.

The fire started at about 1 a.m. on the first floor of a five-story building at what appeared to be a computer store, fire officials said. The blaze was mostly under control within 90 minutes.

Yet when firefighters tried to extinguish the last of the flames with high-expansion foam in the basement and first floor, it actually pushed some remaining fires upwards to the upper floors.

Approximately 200 firefighters were still on site at 4 p.m.

"It's very labor intensive and it can become very dangerous for us, putting people in there in the smoke." said FDNY Chief of Department James Leonard. "What we're really worried about is the collapse of the first floor.

The cause of the fire is still under investigation, the FDNY said.