There were no reports of life-threatening injuries from the collision, which occurred at about 8:50 a.m. local time near Benkelman, Nebraska, derailing two locomotives and three cars, an Amtrak spokesman said.
Seven people were being treated at Dundy County Hospital in Benkelman, spokeswoman Sandy Noffsinger said, describing them as reporting neck and back injuries. Four other people with lesser injuries were sent to other facilities, she said.
Noffsinger said none of the injuries appeared to be life-threatening, though it was possible some of the patients could remain at the hospital for observation.
The California Zephyr train had left the San Francisco Bay area enroute to Chicago on August 24. Passengers were being taken to a nearby high school and Amtrak said it planned to transport them east to their destinations by bus.
The passengers were taken to Dundy County Stratton High School in Benkelman near the Nebraska-Kansas border, the school district confirmed.
The train was running on BNSF Railway Co tracks that were obstructed by the farm vehicle, Amtrak said.
BNSF has temporarily halted trains operating on the line where the accident occurred, but had not yet issued a service advisory to customers, BNSF spokesman Andy Williams said.
The National Transportation Safety Board was still collecting information on the accident and had not yet determined whether it would warrant a full-blown NTSB investigation, spokesman Peter Knudson said.