The train derailed around 1:20 p.m. in a rural area where the Galena River meets the Mississippi, said Jo Daviess County Sheriff's Sgt. Mike Moser. Authorities didn't say exactly how many people were evacuated, but said it wasn't many.
The train had 103 cars loaded with crude oil, along with two buffer cars loaded with sand. A cause hadn't yet been determined. No injuries were reported.
Galena City Administrator Mark Moran told the Dubuque Telegraph Herald newspaper in Iowa that eight tankers had left the track. "Two of those were still upright. The other six were not," she said.
A release from the Jo Daviess County Sheriff's Department confirmed it was oil from the Northern Plains' Bakken region.
The derailment occurred 3 miles (5 kilometres) south of Galena in a wooded and hilly area that is a major tourist attraction and the home of former President Ulysses S. Grant.
Recent fiery wrecks of trains hauling crude oil in the U.S. and Canada, including one last month in West Virginia, have intensified pressure on officials to approve tougher safety standards for railroads and tank cars. The most serious killed 47 people and destroyed the town centre of Lac Megantic in Quebec, Canada, just across the border from Maine, in 2013.
According to the Association of American Railroads, oil shipments by rail jumped from 9,500 carloads in 2008 to 500,000 in 2014, driven by a boom in the Bakken oil patch of North Dakota and Montana, where pipeline limitations force 70 per cent of the crude to move by rail.
Firefighters could only access Thursday's derailment site by a bike path, said Galena Assistant Fire Chief Bob Conley. They attempted to fight a small fire at the scene but were unable to stop the flames.
Firefighters had to pull back for safety reasons and were allowing the fire to burn itself out, Conley said. In addition to Galena firefighters, emergency and hazardous material responders from Iowa and Wisconsin were at the scene.
The ruptures and fires have prompted the administration of President Barack Obama to consider requiring upgrades such as thicker tanks, shields to prevent tankers from crumpling, rollover protections and electronic brakes that could make cars stop simultaneously, rather than slam into each other.
In a statement, the Federal Railroad Administration said it was sending investigators to the Illinois derailment site and that the agency will conduct a "thorough investigation," to determine the cause.
BNSF spokesman Michael Trevino said railroad employees were on the scene and additional personnel were headed there.
Illinois Gov. Bruce Rauner also put state personnel and equipment at the ready for deployment.
The train's destination wasn't immediately known.