By Nafeesa Syeed
The Associated Press

DES MOINES, Iowa — An explosion and fire Monday at a chemical distribution facility northeast of Des Moines sent plumes of thick smoke into the sky and forced firefighters to pull back for fears of more blasts.

Fire departments from throughout the Des Moines area responded to the fire, which was still burning out of control hours after it ignited.

Fire crews set up unmanned hoses on tripods, pouring water on the building and waiting for the flames to die down, said Neil Shultz, a spokesman for the Polk County sheriff's department. Firefighters surrounded the company grounds and were focusing on stopping the fire from spreading.

"Anybody with a fire truck is here," Shultz said.

One worker suffered slight burns and was treated at the scene.

Flames and clouds of black smoke soared above the Barton Solvents facility, and exploding barrels could be seen jetting into the sky. A.J. Mumm, coordinator for the Polk County Emergency Management Agency, said 55-gallon barrels and 300-gallon tanks were exploding and that there were concerns about loaded rail cars and truck tanks on the site.

Police closed Interstates 80 and 235 near the fire for more than two hours before opening them around 4 p.m., after tests showed the air quality was acceptable, officials said. The Federal Aviation Administration advised pilots to avoid the area because of poor visibility, said agency spokeswoman Elizabeth Isham Cory.

Barton Solvents Inc. is a wholesale distributor of industrial chemicals, oils and surfactants under the Barsol trade name. Company president David M. Casten said it wasn't clear what was burning but that a variety of substances were stored at the site, including hydrocarbons and petroleum-based solvents.

Of particular concern was the rail car, which was filled with hexane, a flammable chemical.

Casten said the fire ignited in a warehouse when a substance was moved by pipe from a large exterior tank into a portable storage tank. Casten said he didn't know what substance was being moved or how it ignited.

An explosion at a Barton Solvents plant in Valley Center, Kan., in July prompted widespread evacuations in the community of about 6,000 people north of Wichita. Investigators have said it was caused by static electricity as workers filled a tank that contained a dry-cleaning product.