CHARLESTNON, W.Va. -- Witnesses reported seeing a red fireball and feeling a blast as far away as Charleston, after an explosion was reported at the Bayer Crop Science Plant in Institute at 10:35 p.m. Thursday. The explosion was heard at least as far away as Mink Shoals.Nitro Police Chief Jack Jordan said there were reports of one fatality, but he could not confirm the information shortly past midnight. A Kanawha County Sheriff's deputy said one person was missing. There was one injury confirmed as of midnight, a plant worker who suffered third-degree burns and was taken to the hospital, Kanawha County Manager Brent Pauley said.The deputy said he had heard reports of smaller explosions at the plant, but he could not confirm the information as of midnight. Jordan said shortly after midnight that there were reports of "multiple explosions going off." Other officials reported at least two explosions, and emergency personnel reported a fire still burning inside the plant at 12:30 a.m.At 12:10 a.m. Friday, officials said they still did not know what caused the main explosion. A Bayer plant representative was on the way to the emergency operations center to tell them what was going on, Pauley said.Kanawha County Commission President Kent Carper, who was in North Carolina Thursday night, said he was trying to decide if an evacuation was necessary.The main explosion started in the plant's Larvin unit, Pauley said. The unit is involved in manufacturing pesticides, Nitro Fire Chief Ernie Hedrick said.The unit houses multiple chemicals, and officials didn't know which ones were involved, Pauley said, so they issued the shelter-in-place as a precaution.No flames were visible in the area as of midnight, but a thick haze had settled over the area."The fire is pretty much contained at this stage of the game, but we need to know what's in the air," Pauley said.Joe Saunders, police chief for West Virginia State University, said WVSU was sheltering its students in place. South Charleston Mayor Frank Mullens said his city's residents had been told to shelter-in-place. Kanawha County Metro 911 Director Carolyn Charnock said "everything west of Charleston" was told to shelter-in-place.Police closed W.Va. 25 and Interstate 64 in both directions around the Institute exit. At 11:35 p.m., police blocked U.S. 60 westbound into Nitro, after Nitro police reported the haze forming in the middle and western part of the city.A Putnam County dispatcher reported no shelter-in-place for Putnam County shortly after midnight. Authorities there were dealing with traffic back-ups."We live two miles away and it blew all the curtains in. It was a force through my window that was pretty incredible," Dunbar resident Gail Ferguson said of the initial explosion.WVSU Patrolman Robert Flinn was parked in his cruiser with his back to the plant. "It was like someone shot a giant spotlight on us," he said. "There was a giant mushroom-type cloud about 100 feet high [and] flames shooting from the building."I was just waiting on a customer and all of sudden I felt a big boom, like an earthquake-type deal," said Sue A. Royal, an attendant at the Go-Mart across W.Va. 25 from the Bayer plant. "It looked like lava exploding out of a volcano.""I could feel the explosion then I stepped out on the deck and could see the sky had lightened up," said Bill Raglin, a Kanawha County school board member who lives about a mile outside Institute.Raglin retired from the Bayer plant in 1995, after 35 years. He estimated the plant employs about 500 workers."There's a crew that works there 24 hours a day," he said. "The chemical units have operators round the clock.""When you're working in a chemical plant you don't look forward for something like this but it certainly is a possibility when you're [working with] great volumes of chemicals.""It's not the first time we've ever had an explosion or an release or a fire," he said. "People in the plant are generally trained to deal with it."Located along the Kanawha River about 12 miles from downtown Charleston, the Institute plant site covers about 350 acres. The facility was built in 1943 by the U.S. government for the production of rubber for World War II. The plant was then bought and operated by Union Carbide in 1947, until 1986, when it was purchased by the French firm Rhone-Poulenc for the production of agricultural chemicals. The German company Bayer bought it in late 2001.The plant is best known for making, using and storing large amounts of methyl isocyanate, or MIC, the chemical responsible for the deaths of thousands of people in a huge leak at a Carbide plant in Bhopal, India, in December 1984. Eight months later, 135 people were treated in Kanawha Valley hospitals after a leak of the chemical aldicarb oxime from the then-Carbide plant in Institute.On Aug. 18, 1994, an explosion ripped through the methomyl-Larvin pesticide unit of the plant, then owned by Rhone-Poulenc. One worker was killed and several others seriously injured. One of the seriously injured workers died a decade later from the effects of cyanide that burned his lungs in the blast. Initially, the U.S. Occupational Safety and Health Administration fined Rhone-Poulenc $1.7 million for willful safety violations. OSHA settled the case for $700,000 in fines.In 1996, Rhone-Poulenc paid $450,000 in fines for a leak and fire in February of that year that forced thousands of residents to take shelter in their homes.Earlier this month, the plant announced plans to increase capacity and hire 24 new workers to meet growing demand for Larvin.Federal workplace safety officials last inspected the plant in October 2007 and found no violations, records show.Prior to that, the most recent OSHA review of the plant was in July 2005. Inspectors cited the plant for eight serious and two willful violations.Bayer paid a $110,000 fine to settle the matter, which included violations of rules governing the management of highly hazardous chemicals, according to OSHA records.Federal workplace safety officials last inspected the plant in October 2007 and found no violations, records show.Prior to that, the most recent OSHA review of the plant was in July 2005. Inspectors cited the plant for eight serious and two willful violations. Bayer paid a $110,000 fine to settle the matter, which included violations of rules governing the management highly hazardous chemicals, according to OSHA records.Staff writers Gary Harki, Tara Tuckwiller, Veronica Nett, Ken Ward Jr., James Davison and Greg Moore contributed to this report.