A massive fire sparked early Thursday morning underneath a propane tank in Metro Center.The fire ignited around 5:15 a.m. under the 1,000 gallon tank located outside an office building located at 245 Great Circle Road, across from Athens Way.The fire was extinguished by 8 a.m. after crews entered the building and shut off a valve.While battling the blaze, crews were told to keep away from the fire. A water cannon on top of a fire truck was used to help keep the flames low. The tank is located a few feet away from the office building and the fire did not spread to the structure.However, the building and several nearby were evacuated as a precaution in fear the tank might catch fire and explode."[A] fire truck had come by and said you need to go across the street, it's a 1,000 pound tank and it could blow," employee Monique Stenke said. Employees told Nashville's News 2 at least four businesses work out of the office building including Kenco, a logistics company, and Parallon, a medical services company.The propane is reportedly used to refuel mechanical equipment such as fork lifts.The assistant fire chief told Nashville's News 2 pipes underneath the propane tank caught fire. The exact cause is under investigation.The fire burned underneath the tank for nearly three hours but the tank never exploded.A technician will inspect the propane tank later on Thursday.Employees are expected to be allowed back into building by midmorning.No injuries were reported.