DeWITT, Iowa - About 500 tons of molten glass were spilled in an incident Monday afternoon at Guardian Industries' glass-manufacturing plant in DeWitt, company officials said Tuesday.

DeWitt Fire Chief Bob Sandry said the molten glass "looked like lava flowing down from a volcano."

The glass leak happened during routine maintenance, and six fire departments spent about five hours pouring cold water on the spill, which turned it into glass.

The plant is designed for molten glass to flow into the basement in such an event.

"This is the first time we've had to use it at the DeWitt plant," William Rice, human resources manager for the company, said Tuesday. "The area in the basement is designed to contain the glass. This was a rare occurrence."

Rice estimated about 500 tons of molten glass went into the basement.

"We had an outstanding response from the local community. The fire department worked with our employees," he said.

He had no estimate of the damage or cleanup costs yet, but said the company expects the affected production line to be down for a few days.

Sandry said workers were doing maintenance on an oven when one of the sections came out and the molten glass spilled, flowing three stories down to the basement.

"We were pouring water on it to make it into glass," he said. "They lost several thousand tons of molten glass. There's a huge amount of glass to clean up."

While the fire departments rotated 12 to 15 crew members in and out of the hot temperatures of the plant, Guardian employees remained working and local medical personnel and the Gateway Chapter of the American Red Cross provided support for heat-fatigued firefighters.

Welton, Charlotte, Grand Mound, Long Grove and Low Moor also brought firefighters to rotate in pouring water on the spill, using 400,000 gallons of water. Guardian has its own water tank, and Sandry said DeWitt city crews assisted in making sure there was enough water and pressure for the fire hoses.

Chance Kness, Clinton County emergency manager, arranged for Genesis Medical Center-DeWitt and the Red Cross to stand by to do blood pressure checks for the firefighters and provide food and water.

"This isn't something you can train for. We don't have volcanoes in the Midwest," Sandry said.