REPUBLIC, Mo. (AP) -- Three workers escaped safely when fire broke out in an empty, 1.5 million-gallon gasoline storage tank where they were doing maintenance.

The workers were using cutting torches Wednesday and accidentally ignited a small pocket of unleaded gasoline that had been unnoticed.

Republic Fire Chief Duane Compton said he feared the worst when he saw black smoke pouring from the top of one of the huge white storage tanks at Magellan Pipeline Co.

"They've got about 12 million gallons of gasoline and diesel stored out there," Compton said. "When we saw that smoke coming out the top of one of those tanks we immediately started calling for mutual aid. Things could have gone south in a real hurry."

Springfield and four other neighboring cities sent trucks and crews to the scene.

After getting out of the tank, the workers went back in and put out most of the blaze with dry-chemical fire extinguishers.

The initial fire ignited a secondary fire in the rubber sealing ring around the edge of the internal floating roof. When the tank is being used, the internal floating roof sits directly on the fuel and helps keep explosive fumes from building up inside.

Compton said one of the workers told him that he left the tank for good when the soles of his shoes began melting on the floating roof.

Republic firefighters quickly cooled the internal roof with water and extinguished the fire burning in the rubber seal.

"We were very lucky today," Compton said.