OAK CREEK - Six people were injured in an explosion and fire Tuesday morning at the Oak Creek Power Plant.

The explosion in the plant's coal handling facility was reported shortly before 11 a.m. It started a fire in a silo used to collect coal dust. Six contractors were in the area at the time.

Five people went directly to Columbia-St. Mary's Hospital in Milwaukee for treatment. One person, in critical condition, was transported to the hospital Tuesday afternoon after receiving initial treatment at Froedtert Hospital in Wauwatosa. Officials have not yet released the names of the injured parties.

The explosion and subsequent fire happened in plant's coal handling facility, which serves both the old power plant and the new expansion area, said We Energies spokeswoman Irissol Arce. She did not know what, if any, effect the fire would have on the plant's coal supply but said they don't expect any problems.

We Energies has 350 employees at the plant, Arce said, not including contractors and subcontractors who work there. There are about 2,600 people working at the plant, which is currently undergoing a massive expansion, according to the company's Web site.

During a press conference Tuesday afternoon, We Energies and Oak Creek Fire Department officials described what happened:

Oak Creek firefighters received a call for service at We Energies just before 11 a.m., saying that there had been an explosion.

The Oak Creek Fire Department responded with a full assignment, and requested help from other departments as needed. At least 15 other departments - including several from Racine County - assisted with rescue and fire personnel and equipment.

Oak Creek Assistant Fire Chief Tom Rosandich said the fire started with an explosion in a dust collector, which collects residual coal dust after coal is dumped into the hopper.

There were six contractors working in the silo at the time of the explosion, officials said, putting up scaffolding and preparing to do pipe repair work. The workers are employees of Safway, a subcontractor for Automated Fire Protection.

Flight for Life transported two of the injured workers, one to Columbia-St. Mary's and one to Froedtert. Columbia-St. Mary's has a burn unit.

Kathy Schmitz, a spokeswoman for Columbia-St. Mary's, said all the victims are men between the ages of 22 and 43. Two were treated and released. Three were in fair condition and one was in critical condition as of Tuesday night.

Schmitz said the five men who had come directly to Columbia-St. Mary's received burns to about 10 percent of their bodies, including to their faces, hands and back. They were also treated for smoke inhalation, she said.

"Our prayers and thoughts go out to those individuals and their families," said Barry McNulty, a spokesman for We Energies.

The dust collection silo the contractors were working in was built in November 2007, and was designed to withstand an incident like this with blow-out panels that release internal pressure after an explosion, McNulty said.

He said the plant is stable and continues to operate; there were no interruptions in power service due to the explosion. Construction work at the site was not disrupted, nor was work at the power plant, McNulty said.

McNulty said a full investigation will be done, not only by the fire department, but also the Occupational Safety and Health Administration and likely other regulatory agencies like the Public Service Commission of Wisconsin. Officials interviewed workers who were in the general vicinity of the explosion and fire.

Rosandich said the entire fire was contained within the silo and that it was knocked down within an hour of initial response. Personnel remained on scene for several hours, checking for hot spots.