PETROLIA — No one was injured Thursday morning when a small fire broke out in a hydrogenation unit at the Sonneborn chemical plant in Petrolia, authorities said.

The unit, however, was to be shut down for “a few days,” said plant manager Roman Myrna.

A gasket leak on a heating exchanger in the unit, he said, apparently caused the fire about 8:45 a.m. at the upper section of the sprawling plant.

Two employees were supervising the unit, which is used in the chemical manufacturing process, when they noticed a small flame.

The operators threw the emergency shut-off and pulled the alarm to notify guards, who called 911, officials said.

But by the time Petrolia, Bruin and Parker volunteer fire departments got there the fire was out.

“It was small enough that the operators were able to put it out with a fire extinguisher,” Myrna said.

The unit will remain shut down until the company completes an investigation, and repairs are made.

“It won't hamper customers,” Myrna said.

About 160 employees work on site at the Sonneborn plant, which makes products such as petroleum jelly, baby oils and waxes.