Carroll County crews spent about five hours yesterday battling a fire in a two-story mulch pile at a construction company's property off Route 97 outside Westminster, fire officials said.

The call about the blaze came in about 4:10 a.m., and within 15 minutes, firefighters had found the mulch pile, said Robin Stansbury, a Westminster fire spokesman.

Firefighters grew alarmed as the fire began moving down one side of the mulch pile toward a building about 50 feet away where equipment and chemicals were stored.

"We were afraid of radiant heat catching that on fire," Stansbury said.

Because the mulch pile is about a quarter-mile from the driveway of C.J. Miller -- an excavation, paving and construction company in the 1000 block of Meadow Branch Road -- firefighters were pumping water from holding tanks on the road, Stansbury said.

He estimated that about 50 firefighters were on the scene, including a tanker unit from Adams County, Pa., just over the Carroll County line.

Although the surface fires were under control by about 6:30 a.m., crews had to dig into the mulch pile to check for signs of smoldering, Stansbury said. Fire officials said crews cleared the scene between 9 and 10 a.m. The cause of the blaze and extent of the damage were being investigated.

State police said the fire slowed rush-hour traffic along Westminster's busy Route 97 corridor.

Mulch fires are more common and hazardous during dry spells, said Jane Edwards, a program manager with the state fire marshal's office. Mulch fires are often ignited by discarded cigarettes, she said.

"It's sort of like a campfire," Edwards said. "They can smolder and then erupt into flames."

jennifer.mcmenamin @baltsun.com laura.mccandlish@baltsun.com