(Adds expected reopening of mainline track on Monday)
March 7 (Reuters) - Firefighters were still working on Saturday to extinguish several blazes that erupted when a BNSF Railway train loaded with crude oil derailed two days ago in a rural area of northwestern Illinois, a local official said.
The incident marked the latest in a series of derailments in North America involving trains hauling crude oil, heightening focus on rail safety.
Nobody was injured in Thursday's fiery wreck, in which 21 cars of a 105-car train that originated in North Dakota derailed on the mainline track about 3 miles outside Galena, a town of just over 3,000 near the Wisconsin border.
Five of the 103 cars packed with Bakken crude oil caught fire, sending plumes of black smoke and fireballs over the area, city and company officials said.
By Saturday, several minor fires were still burning in the toppled cars but crews expected to extinguish the lingering blazes by later in the day, said Galena City Administrator Mark Moran.
BNSF said in a statement it anticipates its mainline track will be operational on Monday.
Local, state and federal officials were on scene to assess damage and environmental contamination in the area, a heavily wooded region near the confluence of the Galena and Mississippi rivers.
"We're of course concerned over potential environmental impact," Moran said. "BNSF said there's no apparent groundwater impact and air quality tests are good."
BNSF, a unit of Berkshire Hathaway Inc, said in a statement on Friday that the cause of the derailment was under investigation.
The company also set up a claims center to help residents who may have suffered property damage or need temporary relocation.
"BNSF continues to take precautionary measures to protect the waterways in the area and continues to conduct air quality monitoring. BNSF will address any environmental impacts," the statement said.
About 40 to 50 oil trains come through the region each week, local officials said.
The accident is the latest involving oil trains in the United States and Canada, including the derailment of a Canadian National Railway Co train earlier on Saturday.
The train went off the tracks in the Northern Ontario community of Gogama, with the crew reporting a fire but no injuries.
In 2013, some 47 people were killed in the Quebec town of Lac-Mégantic after a train carrying crude oil derailed and exploded. Another recent incident occurred in West Virginia three weeks ago. (Reporting by Victoria Cavaliere in Seattle; editing by James Dalgleish and Matthew Lewis)