UPDATE: Early Morning Fire Guts Vacant Concord Commercial Building

CONCORD (CBS SF) -- Firefighters battled a massive fire early Monday that erupted in a vacant commercial building that formerly was home to Lin's Buffet near Six Flags Hurricane Harbor in Concord.

Fire officials said they received a 911 call reporting the fire in a building near Willow Pass Rd at Water World at around 2:40 a.m. Arriving fire crews encountered a building engulfed in fire with towering flames roaring out of the roof.

The building's windows were boarded up.

"We opened the windows up, there was extensive fire in the building, so it had a good start on us," said Contra Costa Fire Protection District Battalion Chief Dominic Ciotola. "It was through the roof when we got here."

Additional resources were called in. At the height of the firefight there were 4 ladder trucks dumping hundreds of gallons of water on the blaze.

The intensity of the fire forced firefighters to take a defensive approach to battling the blaze. It took about an hour to knock down the flames.

There were no injuries reported and a cause remained under investigation. Ciotola said transients have been living inside the building.

"The structure did not have gas or electric and it was completely boarded up," he said.