OCEANSIDE --- A kettle of roofing tar caught fire Friday morning at a construction site at the Oceanside Museum of Art, but firefighters quickly knocked down the 20-foot flames before any structural damage occurred, a fire captain said.

The close proximity of firefighters -- Fire Station 1 is located next door -- probably prevented a major blaze that could have spread to adjacent structures, Oceanside Fire Capt. Eric Bertotti said.

"They were lucky," Bertotti said. "We were all lucky. I guess that's the benefit of doing construction next to a fire station."

Bertotti said he was sitting in his office around 9 a.m. when he saw heavy smoke outside and flames licking the sides of the museum's 16,000-square-foot expansion project, which is still in the framing stages of construction.

Workers on site were already evacuating, and roofers were attempting unsuccessfully to put down the flames with fire extinguishers, he said.

Within 45 seconds, firefighters were spraying water on the building, he said.

There fire caused no injuries and contamination from the water-tar mix was minimal, Bertotti said.

From a fire protection standpoint, a building in the framing stage is at its "most vulnerable," as the wood skeletons can burn quickly, Bertotti said.

Earlier this year, Escondido suffered the worst fire in that city's history when flames ripped through a huge condominium complex that was at a similar stage of construction,

Upon completion, the museum expansion in the heart of downtown will house two galleries, a conference room and a research library.