SAN FRANCISCO (CBS 5) — A man was hospitalized Wednesday evening with life-threatening, third-degree burns after somehow catching fire inside a San Francisco porn store, authorities told CBS 5.

The fire occurred at the Golden Gate Adult Superstore at 99 Sixth Street, near the intersection with Mission Street, in the city’s South of Market neighborhood around 6:20 p.m.

READ MORE: Dixie Fire Update: New Evacuation Orders For Lake Almanor Communities; Flames Threaten Greenville

Police officers across the street from the porn shop saw a man run out the front door of the store “engulfed in flames,” SFPD Lt. Kevin McNaughton said.

Some firefighters who happened to be about a block away at the time were immediately summoned and extinguished the flames.

READ MORE: Fourth Stimulus Check: Are We Any Closer To Another Relief Payment?

Arson investigators said it was not exactly clear how the man caught fire. Police indicated he had apparently been watching videos in a private booth at the adult arcade when the fire ignited.

The man, whose name has not been released, was being treated at St.
Francis Memorial Hospital for severe burns over 90% of his body.

MORE NEWS: San Francisco Library Reopening 11 Branches Over Next 2 Weeks

(Copyright 2011 by CBS San Francisco. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)