A two-alarm fire early Tuesday gutted a Waldorf restaurant and closed down southbound Route 301 for two hours just before the morning commuter rush.

The fire at the Great American Steak and Buffet Co. at 3135 Crain Hwy., which was reported by a passerby at 5:24 a.m., was ruled accidental.

Duane K. Svites, deputy chief state fire marshal, said it began in the venting above the kitchen when the grease that had collected there was ignited. The fire spread from the attic into the serving area and wound up engulfing the entire building.

He said the building's venting and its sprinkler system complied with building codes.

The state fire marshal's office estimated the blaze caused $1.5 million in damage. About 100 firefighters from departments in Charles and Prince George's counties responded to the blaze, said Nina Voehl, public information officer for Charles County's government.

She said part of southbound 301 was closed about 6 a.m. and reopened just before 8 a.m.

No one was injured in the fire.

Just before noon Tuesday the chain's regional manager stood at the scene of the fire with the Waldorf restaurant's general manager, Joe Loghry, and stared at the blown-out windows, collapsed blue roof and twisted white siding.

The Great American Steak and Buffet Co. employed 55 people at the Waldorf location, Loghry said, and they will be without work for at least three or four months until the restaurant can reopen.