A six-alarm fire damaged an Alexandria warehouse yesterday, causing a partial roof collapse and billowing clouds of black smoke that were visible for miles.

More than 200 firefighters fought the blaze, which began shortly before noon inside the low-slung building at 801 S. Pickett St.

Firefighters first attacked from inside the building but were evacuated after part of the roof collapsed, said Robert Rodgriguez, Alexandria’s fire marshall.

No one was inside when the fire started, he said, and no firefighters were injured. By mid­­­afternoon, he said, the fire had been “contained.” Firefighters have not determined a cause, he said.

Ace Recycling, a waste disposal business, is listed as a tenant of the building. No one from the business could be reached.