KELLER -- Firefighters have gained control of a massive fire that included exploding fuel cylinders at Keller Outdoor Power in the 400 block of North Main Street.The fire started about 1:30 p.m. Thursday at the business that sells commercial and residential outdoor power equipment. It was contained by 3:30 p.m.Keller Fire Chief Dan Gaumont said their department is about two blocks away and "when we pulled out there was smoke blanketing over the highway."The smoke was so thick that Main Street, also known as U.S. 377, had to be shut down from Keller Hicks Road to Mount Gilead Road.Employee Billy Stewart was outside working on a car when he said he smelled an electrical fire."I opened the door of the shop and saw the entire wall on fire," Stewart said. "It was totally engulfed."Stewart said he found the employees inside and two customers and everyone got out of the building safely."That was my main concern," Stewart said.Firefighters from 15 departments, including Keller, Fort Worth, Trophy Club, Colleyville, North Richland Hills, Westlake and Grapevine were battling the fire -- while also dealing with triple-digit temperatures.Volunteers were bringing bags of ice and water to assist the firefighters."When it's this hot it doesn't take long to get dehydrated," Gaumont said. "Those guys have 80-pound suits on that don't breathe."Gaumont said firefighters were rotated every 20 minutes and that they did not enter the building because of safety concerns."There were six 55-gallon drums of racing fuel and several propane cylinders inside the building," Gaumont said. "While we were fighting the fire they exploded."The business, a former feed store, is valued at $612,150 by the Tarrant Appraisal District.Gaumont said that one of the business' two buildings was destroyed and will likely be a total loss.