Two trains, one including cars carrying ethanol, were involved in an accident around 1:15 p.m. Friday (2:15 p.m. ET) in Porter County, Indiana, authorities said.
Aerial video footage showed smoke and flames rising from jumbled train cars. It was not clear how the trains made impact.
There was no immediate word on casualties.
Ethanol "is a very volatile flammable liquid and it will take multiple units from the fire department to douse and put this out, said David James of the county's highway department. Area roads have been blocked off.
The accident occurred on a CSX line about 30 miles southeast of Gary, he said.
James had no further details.