HARPERS FERRY, W.Va. (AP) — A freight train derailed as it crossed the Potomac River near Harpers Ferry, West Virginia, sending two cars into the water and damaging a footbridge that is part of the Appalachian Trail.

CSX said in a statement that there were no injuries early Saturday morning when seven cars in total derailed. CSX said all the cars were empty and no hazardous materials were involved.

CSX said the cause of the derailment is under investigation and it will work swiftly to clean up and restore the area.

The National Park Service said the derailment closed access to some parts of Harpers Ferry National Historic Park and the Chesapeake & Ohio National Historic Park.

Photos released by the park service showed damaged to a footbridge that's attached to the CSX bridge and is a part of the Appalachian National Scenic Trail. The park service said that footbridge was closed indefinitely and referred hikers to the Appalachian Trail Conservancy for updates.