CARLSTADT, N.J. (CBSNewYork/AP) — Officials have closed the Carlstadt Post Office following an early morning fire.

The flames broke out near the roof of the building on First Street around 1:30 a.m. Thursday. The post office is on the ground floor and an electrical supply store is on the top floor.

“I looked out the window and all you could see on this side of the building was all the flames going up into the air, tons and tons of smoke,” said nearby resident Robert Morgan. “It’s scary.”

“I saw flames shooting out, shooting out of the back of the building too, and I tell you, it really scared me,” witness Gail Van Miert said.

The roof partially collapsed from the fast-moving flames and firefighters who were inside made it out just in time.

“All of a sudden my guys stared advancing in and I saw it come down and I told them to get out right away,” Carlstadt Fire Department Chief Rob Popejoy told CBS 2’s Janelle Burrell.

The fire gutted the electrical supply store and caused significant water damage to the post office.

Ron Malkenson, owner of Mdr Electrical Supply, said work was being done on the roof over the last couple of days and questions whether that work may have led to the fire.

“The roofer was working on the building and we’re wondering how it happened cause the roofer was doing something on top of the building,” Malkenson said.

No one was inside the building when the fire started. Two firefighters suffered minor injuries.

A spokesperson from the postal service said customers shouldn’t be too concerned because the packages inside the post office were mostly parcels that carriers had been unable to leave without a signature, Burrell reported.

Post office reps said there was a minimal amount of mail inside the building during the fire and Thursday’s delivery had not yet arrived.

Post office boxes and mail pick-up are being transferred to the East Rutherford Post Office at 193 Park Avenue.

A postal spokesperson said Carlstadt customers can expect uninterrupted delivery.

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