CLARK COUNTY, Ky. (WKYT) - Firefighters tell us it was a close call.

The fire broke out around 8 p.m. Friday on Mount Sterling Road in Clark County, not far from the Montgomery County line.

The Clark County Fire Department called in mutual aid from Montgomery County to the fire here at the auto shop because they call fires like these firefighter killers.

"It was really full of hazards, so we had to be cautious yet aggressive to stop this fire," said Battalion Chief Ernest Barnes with Clark County Fire.

The black smoke that these firefighters could see outside the building was not the main concern.

"We heard some pops when we first got here and were preparing to make our attack and that certainly makes us a little more cautious than usual once things start to go," said Battalion Chief Barnes.

It was what the auto shop stored inside.

"It was definitely a scary situation. We had at least three vehicles inside the structure. We don't know if they had gasoline and oil in them," said Battalion Chief Barnes. "We don't know if there's gasoline storage inside the facility. We knew there was a barrel of oil inside. There could be paint, chemicals, and a number of different kinds of chemical hazards inside."

After investigating fire officials say the cause of this fire was a homemade oil burning furnace located in the shop.

The home connected to this auto shop garage was not damaged in the fire, but firefighters did open doors and windows to ventilate the home.

We are told no one was injured in this fire.