LA PORTE, Ind. -- Two Norfolk Southern freight trains collided at La Porte, Ind., early Sunday morning, injuring four crew members and derailing 25 cars, according to Trains.com.

Westbound train 19A, with two locomotives and 125 cars, en route from Pittsburgh to Chicago, was struck head-on by eastbound train X2G, hauling steel from Burns Harbor to Elkhart, Ind., and consisting of two locomotives and 148 cars. The collision occurred at 2:29 a.m. at CP-463, an interlocking on NS’s former Conrail main line between Cleveland and Chicago.

The westbound train had begun to cross over from Track 2 to Track 1 when it was struck by the oncoming eastbound, reported the South Bend Post Tribune. The impact derailed train X2G’s two locomotives and 25 cars from both trains. A small amount of diesel fuel leaked, but was contained. Derailed boxcars blocked grade crossings near the accident scene and damaged two buildings adjacent to the right of way.

Each train was occupied by two crew members. Three employees were treated and released; the fourth was hospitalized with a concussion, reported the News Dispatch.

Amtrak passengers on the westbound Capitol Limited and Lake Shore Limited were bused from South Bend, Ind., to Chicago on Sunday morning.

NS returned one track to service on Sunday afternoon, and returned the second one to service early Monday morning.

The cause of the crash is under investigation.