WEST WINDSOR Twp, N.J. (CBS) – Police and emergency crews are investigating a multi-vehicle accident in Mercer County involving an RV.

The accident took place just after 3:30 p.m. on Route 1 Northbound in the area of Quaker Bridge Road in Windsor Township.

An RV was overturned, closing all lanes. Police warn drivers to expect heavy delays in the area.

A medical helicopter has landed at the scene of the crash in response to an injury.

The cause of the crash, as well as the extent of the injuries are unknown.