By Matt Smith and Deanna Hackney
(CNN) -- A pillar of black smoke billowed over downtown Lynchburg, Virginia, after a train carrying crude oil jumped its tracks and caught fire Wednesday afternoon, city officials said.
Between 12 and 14 cars from a CSX freight train were involved in the derailment, which occurred along the James River and left oil burning along the river's surface, city government spokeswoman JoAnn Martin said.
About 50,000 gallons of crude oil are missing from the tankers, she said. It's unclear how much of the oil burned in the blaze and how much spilled into the water.
Buildings near the derailment were evacuated for several hours, and firefighters let the fire burn out on its own, she said.
Travis Uhle was working at the Depot Grill when he came out and witnessed the crash.
"You just saw it going sideways on two wheels and then one went down, and the train just kept on coming," Uhle told CNN affiliate WDBJ. "And then just a dogpile on top of that."
At least three tank cars fell into the river, a photograph taken at the scene showed. Lynchburg police Lt. David Gearheart said the fire was contained, but still burning, four hours after the derailment.
CSX said three of the cars caught fire after the derailment, the cause of which wasn't known Wednesday.
"CSX is responding fully, with emergency response personnel, safety and environmental experts, community support teams and other resources on site and on the way," it said. "We are committed to fully supporting the emergency responders and other agencies, meeting the needs of the community and protecting the environment."
William Hayden, a spokesman for the Virginia Department of Environmental Quality, said it was "too soon to say" what the environmental impact of the accident would be. The spill was contained before it stretched more than a quarter of a mile downriver, he said, but it wasn't clear Wednesday evening how much oil had spilled into the James.
"We have people on the scene providing technical assistance to make sure the leak is contained properly," Hayden said.
An oil boom in North Dakota and Canada has led to a fourfold increase in the amount of crude shipped by rail since 2005, according to the U.S. National Transportation Safety Board. Environmentalists and regulators have been paying more attention to those shipments since a July derailment and fire killed 47 people in a small town in Quebec.
In March, environmentalists warned against having trains hauling oil from North Dakota's Bakken shale pass through downtown Lynchburg en route to a storage depot in Yorktown. Glen Besa, director of Virginia's Sierra Club chapter, said Wednesday's accident only heightens those worries.
"This train track runs right through the heart of Richmond, by the way. This could easily have happened in the heart of the capital city," Besa said. He said it wasn't clear whether the oil would burn off completely without leaving residues on the ground or in the river.
"These are the questions that should have been asked before we started doing this," he said.
Casey Hernandez, a spokeswoman for the U.S. Department of Transportation, said Virginia received just under $400,000 last year in Hazardous Materials Emergency Preparation grants. She noted, too, that the department has held two all-day hazmat transportation training workshops in the state since September.
The volume of oil spilled or burned wasn't immediately known. The NTSB and the Federal Railroad Administration are sending investigators to the site, those agencies said.
The U.S. Environmental Protection Agency was monitoring the air at the request of state officials, EPA spokeswoman Enesta Jones said.
Martin said Lynchburg's drinking water wasn't affected by the spill. But in Richmond, more than 100 miles downriver, authorities have begun drawing drinking water out of a separate canal rather than the James as a precautionary measure, said Angela Fountain, a spokeswoman for the city's Department of Public Utilities.
John Aulbach, director of the state Office of Drinking Water, said it would take three to four days for any oil that may have spilled to reach Richmond, and it would be "very diluted" before it reached that point. Other communities can bypass the river as well.
"We're not expecting any effects to drinking water," Aulbach said.
CNN's Athena Jones, Cristy Lenz, Greg Seaby, Greg Botelho, Kevin Conlon, Matthew Stucker, Jonathan Helman and Mike M. Ahlers contributed to this report.
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