Officials investigate plastics plant explosion that killed 4
(CNN) -- Noting the scope and toll of the accident, state and federal officials have launched an investigation into an explosion at the Formosa Plastics plant in Illiopolis, Illinois, that killed four company workers and injured four others, company spokesman Rob Thibault said early Monday.
"We don't know the cause of the explosion," said Thibault of Friday night's deadly blast at the company's resin plant. "It's being investigated by state and federal agencies."
The Environmental Protection Agency, the U.S. Chemical Safety and Hazard Board (CSB), the Illinois Department of Environmental Protection and Formosa Plastics Corp. all have a role in the investigation, he said.
Calling the accident "among the most serious that the [CSB] has investigated in more than six years," CSB Chairman Carolyn W. Merritt said a full investigation is being conducted.
"Based on the human toll, the damage to the plant, the hazards of the materials used, and the impact on the public, the U.S. Chemical Safety Board has begun a full, independent, federal investigation of the root causes of the disaster at Formosa Plastics."
Merritt said the investigation could take a year or more to complete.
The CSB is an independent federal agency charged with investigating industrial chemical accidents.
There were at least 16 employees working Friday night at the Formosa Plastics plant near Illiopolis -- about 20 miles east of Illinois' capital, Springfield -- when the initial blast happened around 10:40 p.m. (11:40 p.m. ET). Two or three subsequent explosions followed.
"I heard reports that the blast was seen or heard as far as 20 miles away," said Sangamon County Sheriff Neil Williamson.
Of the four injured, Thibault said, two are in critical condition and the others are listed as serious and fair.
According to the Formosa Plastics Corp. Web site, its Illiopolis plant manufactures polyvinyl chloride (PVC) resins.