At least four people have been injured in a two-alarm fire at a warehouse in Newark.

The fire started just before 5:30 p.m. at a warehouse for Boasso America, located at 80 Doremus Ave.

Witnesses reported seeing large plumes of black smoke from miles away. Others say they heard loud explosions coming from inside the building. But authorities say the cause of the fire has not been determined.

Fire officials say the explosion caused structural damage to the building and a partial roof collapse.

Three people were initially reported as being injured in the blaze. Several hours later a fourth person was found injured among the rubble.

One of the victims was taken to St. Barnabas Medical Center in Livingston. The others were taken to University Hospital in Newark.

The conditions of those injured remains unknown. They were all employees at the warehouse.