GREENDALE, Ind. (AP) -- A fire at a southeastern Indiana plastics recycling factory burned so hot that it melted firefighters' helmet visors and caused the building's concrete to crack.
The blaze at the Alternative Plastic Services plant continued to burn Friday, more than 20 hours after it started, and firefighters decided to let it burn itself out, Greendale Fire Chief Ed Noel said.
As many as 100 firefighters from Ohio, Kentucky and Indiana were at the scene Thursday before officials decided to pull them out of the six-story brick building about 20 miles west of Cincinnati after growing cracks were seen in the concrete.
A shelter was opened at a middle school in nearby Aurora for people with respiratory problems. Environmental agency workers were monitoring the smoke from the fire and had determined that the air quality was still good, police said.
At least four firefighters were taken to the Dearborn County Hospital, suffering from apparent heat exhaustion.
Officials had not determined what caused the fire at the 200,000-square foot building, which sent out huge plumes of black smoke that could be seen from miles away.
''I will say, I don't think I've ever been in a fire this hot,'' said Lt. Kevin Turner of the Aurora Fire Department.
According to the company's Web site, the business grinds up used plastic products and resells the material.
About 50 to 75 people work there, said company salesman Greg Winans. He said none was hurt.
The company has been operating for 12 years in two of the buildings that had housed the Schenley Distillery, which closed in 1988.
The two buildings are part of a 200-plus-acre industrial complex, most of which has been abandoned.
State Fire Marshal Roger Johnson said he did not know whether any problems contributed to the fire, such as whether sprinklers were working.