A Gwinnett County fast food restaurant was heavily damaged by fire early Wednesday.

The blaze at the Taco Bell restaurant in the 1800 block of Grayson Highway was reported by a passing motorist at 7:15 a.m., according to Gwinnett fire Lt. Eric Eberly.

Firefighters found heavy smoke coming from the roof and sides of the building, and were able to quickly control a large fire in the ceiling of the restaurant, Eberly said.

No one was inside when the fire broke out, and no injuries were reported.

Eberly said the cause of the fire, which extensively damaged the interior of the business, has not been determined.