HOPE MILLS, N.C. — Investigators have ruled that the cause of an explosion and fire at a Cumberland County propane company Thursday evening was an accident.

Witnesses said there were two explosions before the fire broke out at Jenkins Gas and Oil Co., Inc. on Legion Road just before 7 p.m.

"I swear it felt like someone dropped a bomb on us," witness Frank Quinn said.

"It was like the Fourth of July. People crowded around, trying to watch fireworks up and down the street," witness Christina Shipman said.

Firefighters said it started in and around propane trucks, then spread to the building, melting the roof. Investigators said two employees were working on a valve when something ignited the gas.

Three employees were transported to Cape Fear Valley Medical Center for treatment. They were later transferred to University of North Carolina Hospitals in Chapel Hill.

Gary Garner, Steve Jackson and Jay Sharpe are listed in critical condition.

Residents and businesses within a one-mile radius of the gas company were urged to leave the area as a precaution.

"We evacuated neighborhoods near the building and some businesses near the structure. We opened up a shelter and there were approximately 10 people taken there," said Ronnie Marley, Pearce's Mill Fire Chief.

Twenty-two fire trucks responded and crews spent three hours fighting the fire before allowing it to burn itself out.

Residents were allowed to return to their homes at about 9:30 p.m.

Fire crews returned early Friday after a small fire reignited. Hazardous materials crews were also called after fumes were detected at about 7 a.m.