OKLAHOMA CITY - A man is recovering after a four alarm Oklahoma City fire Sunday.

It took hours for crews to put out the flames near Pennsylvania Ave. and Exchange Ave.

The building that burned down is across from a fire department, but that didn’t make putting out the flames any easier,

Black smoke could be seen from miles away, as the fire took over the structure,

Carl Sandefer and his friends stored and repaired cars in the building.

“I can't for the life of me figure out why it's burning so bad,” Sandefer said.

Sandefer says his cars didn’t have much gas in them.

“That's just crazy. It's burning so bad. I mean, it's got to be the roof,” Sandefer said.

Firefighters say it was indeed the roof that caused this fire to take over the structure.

“The type of construction that the roof is, it's a wood type of truss, they're prone to a catastrophic failure whenever they do fall in,” Oklahoma City Fire Deputy Chief of Operations Mike Walker said.

The only person in the building got out well before the roof fell in, and was treated for smoke inhalation.

“A person who was in the building across the street came and knocked on the door, at Station Eight, and informed that there was a building on fire. One of the cars that they were working on caught on fire,” Walker said.

The fire attracted dozens of spectators for the hours it burned.