Crews worked overnight to clean up heaps of coal that spilled after 21 train cars derailed Monday in Nicholas County.

It was not immediately clear what caused the derailment, which happened just after 4 p.m. in Carlisle on Concrete Road across from a mobile home park.

There were 107 rail cars carrying coal to Maysville, Nicholas County Sheriff Dick Garrett said. Each car had a capacity to carry 100 tons of coal, said Noel Rush, spokesman for R.J. Corman Railroad Group, the company that is clearing the spill. Rush did not know whether the cars were filled to capacity.

Rush said the cleanup should be finished by the end of Tuesday. The train belonged to TTI Railroad and had three crew members on board, said Russ Rogers, president of TTI.

Ashlee Clark and Karla Ward