La Crescent Fire Chief Bernie Buehler says the accident happened about 5:30 a.m. Wednesday near Dresbach, at the southeastern corner of Minnesota.
Buehler says two railroad employees on the trains were injured.
The immediate area has been evacuated because the accident caused a propane leak at a switching station. Winona County Emergency Management spokesman Dave Belz says liquid ammonia is leaking from some cars, too, but isn't a public danger.
Buehler says one train had 100 cars, and the other had 15. Some of the cars ended up in the Mississippi River. Crews could see fewer than half of the cars left standing.
Information from: WXOW-TV La Crosse.