HELENA, Mont. - Passengers on Amtrak's Chicago-Seattle train were moved to buses for part of their Montana travel on Monday after a BNSF Railway freight train derailed, blocking tracks and spilling corn destined for export from the West Coast.

Ten cars in a 110-car train hauling corn from Halloway, Minn., to Tacoma, Wash., derailed at about dawn, 45 miles east of Libby in northwestern Montana, said Gus Melonas, a spokesman for Texas-based BNSF. Corn spilled in previous derailments farther east, near Glacier National Park, was controversial because grain not cleaned up attracted grizzly bears, and trains struck and killed eight of them in the 1980s.

Melonas said vacuums would remove the corn spilled Monday.

"We are mobilizing equipment to make sure we don't attract any wildlife," he said, adding he did not know how much corn was on the ground. The derailment area "generally is not a grizzly bear area, but we've had some bears in recent years drift over from the Whitefish Range, in that direction," said Jerry Brown of the Montana Department of Fish, Wildlife and Parks.

Melonas said the track likely would reopen Tuesday, but removing rail cars from the area could take up to three weeks.

Blockage of the track required that passengers on Amtrak's Empire Builder, which crosses the state's northern tier daily, travel by bus for the 250 miles or so between Libby and the Montana town of Shelby.