Highway 5 to Fort Smith, N.W.T., was closed to traffic for several hours Monday morning, after a large section of the road collapsed overnight.

The affected section of road was 164 kilometres from Fort Smith, near the Nyarling River.

Officials with the Transportation Department described the collapsed area as a "crater-like" hole about six metres wide and six metres deep — large enough to swallow a car.

Highways supervisor Art Barnes said barricades were set up, and staff have remained on site since dawn to stop and redirect traffic.

Light traffic was being allowed to pass around the hole Monday afternoon, but the highway remained closed to heavy vehicles.

Officials said the collapse was caused by a naturally occurring sinkhole, in which underground springs dissolve limestone or gypsum in the road bed, creating an underground cavity.

Crews are assessing the damage and deciding what will be needed to restore the road bed.