A train hauling coal derailed Tuesday in Nebraska, marking at least the fourth time in less than a month that a freight train has gone off its rails nationwide.

The Union Pacific train derailed two weeks after a Norfolk Southern derailment in Ohio that spilled a flammable gas near East Palestine, setting off a public health scare and fueling calls for stricter regulation and higher fines for railroad safety breaches.

In the latest incident, about 31 cars carrying coal derailed about 1:45 a.m. local time near Gothenburg, Neb., Union Pacific said in a statement. The Omaha-based railroad said that there were no injuries and that no hazardous materials were involved.

Images from Nebraska on Tuesday showed toppled train cars and piles of coal near the tracks as crews worked to clear the debris. Union Pacific said one of three mainline tracks near the derailment site reopened about 8 a.m. Tuesday.