The fire department says the flames that broke out at a car salvage yard in the Bronx yesterday appear to be suspicious.

But the cause of the 5-alarm salvage yard fire, where no one was expected to be at the time, remains unknown, according to fire officials.

The fire burned for nearly five hours and grew so hot that some cars outside the yard caught fire.

More than 200 firefighters responded to the scene at 528 Drake Street in Hunts Point. The first crews were dispatched around 4:30 p.m., just minutes after the first call. The fire was under control just after 9:00 p.m.

Seven firefighters were injured in the fire. Five suffered minor injuries and two suffered serious, non-life-threatening injuries.

When the fire department arrived there was not only a heavy fire, but also an explosion. One of the biggest contributing factors to the rapid spread was the presence of wood pallets and vehicles. 

Fire officials say the fire marshal was called to the scene to investigate the cause of the blaze, as they say no one should've been there. 

“It is a holiday weekend and we believe the business was closed. It was a very large volume of fire upon arrival so we’d like to investigate and know why that happened” said Richard Blatus, FDNY Assistant Chief Bureau of Operations.

One firefighter suffered a minor injury, according to fire officials.