SHARON — Spontaneous combustion of woodworking materials caused a fire that destroyed a garage in Sharon early Monday morning, according to a fire official.

When firefighters arrived at 81 Turnpike Road after being called out at 4:30 a.m., the garage was engulfed in flames, and the fire had spread to a nearby log cabin, according to a Facebook post by Peterborough Fire and Rescue, which covers Sharon.

Peterborough Fire Chief Ed Walker said the blaze was caused by a mistake he called “all too common.” People at the property were using a urethane stain while woodworking in the garage, and disposed of urethane-coated rags in a bucket, which later spontaneously combusted, he said.

“You can ball them up, and they generate enough heat to start a fire,” Walker explained. “It was unintentional.”

The two adults occupying the residence made it out safely, along with their dog and cat. Jaffrey and New Ipswich fire departments were the first on the scene and quickly worked to extinguish the fire on the outside of the home before putting out the garage fire, according to the Facebook post.

The garage collapsed due to the fire, but the adjacent log cabin, which was built from heavy timber, sustained minimal damage, Walker said.

In typical homes, he explained, the materials making up the siding and roof are thinner and have more ventilation, allowing a fire to spread more quickly. Due to the thicker material of the log cabin, he said, the fire burned more slowly.

“There was no fire damage in the house,” Walker said. “There was some smoke damage, but no fire damage.”

Mia Summerson can be reached at 352-1234, extension 1435, or Follow her on Twitter @MiaSummerson.