FARGO, ND (KXNET) — A four-vehicle crash north of Fargo Thursday night turned into a six-vehicle crash after a semi ran into a North Dakota Highway Patrol car that had stopped to investigate the initial crash scene.

The patrol car parked in the passing lane around 7:00 p.m. on Interstate 29 north with its lights flashing. The four vehicles involved in the initial collisions were blocking this lane and the trooper had exited his car to assist those involved in the crash.

Soon after, a semi towing an empty cattle trailer came upon the highway patrol car and struck the rear of the vehicle. The semi then jack-knifed into the median of the interstate.

Neither the trooper or the semi driver were injured in that crash.

There’s no word on injuries to the people involved in the earlier four-vehicle crash and no information yet on the cause.

Northbound I-29 was closed between Argusville and Gardner for about two and a half hours while the crashes were investigated.

The North Dakota Highway Patrol was assisted by the Cass County Sheriff’s Office and the Argusville and Harwood Fire Departments.