Traffic is grinding to a halt on the Perimeter Highway in the aftermath of a serious collision.

The collision occurred around 8 a.m. on Thursday, on the southwest Perimeter Highway, northwest of McGillivray Blvd.

Witnesses say at least one car was involved, landing on its roof in the median. 

Northbound traffic is down to one lane past the scene and is extremely slow.

Callers to the station say that southbound traffic had come to a complete stop. However, as of 9 a.m. the right-hand lane was open again. 

Traffic remains extremely backed up as a result.

There is no word yet on the cause of the crash or if there are any injuries.

If you have an update to share on traffic in the area you can call or text on the Dead Horse Sales & Rentals Talk & Text Line at 1.877.951.2486.

More to come.