PHOENIX - A fire broke out Wednesday morning at 3:45 a.m. at an office building near 21st and Glendale avenues.

When fire crews first arrived, they said the fire appeared to have started in an outside fenced-in storage area. The flames then spread to the attic.

More than 50 firefighters responded to the first-alarm fire.

The lease owner was using the building to store items that he bought from swap meets with the intention of resale.

Phoenix fire said the building was full of contents, making it difficult to gain key tactical positions.

Firefighters said the supplies are a total loss.

The roof structure was heavily involved and ultimately sagged into the interior of the building.

No word on the cause.