Freezing rain and slippery conditions overnight are likely to blame for a massive chain-reaction crash on B.C.'s Coquihalla Highway just south of Merritt.

The highway was shut down at around 10 p.m. Thursday night when a transport truck lost control between Merritt, B.C. and the old toll booth.

When all the slipping and sliding was over, eight semi-trailers, a Greyhound bus and five other cars or pick-up trucks were badly damaged.

Miraculously, only five people were slightly hurt -- and four of them were among the driver and 23 passengers aboard the Greyhound.

The highway was closed for about seven hours while the wreckage was cleared away, but traffic is moving again as RCMP continue to investigate the cause of the accident.

The accident is raising questions about the quality of road maintenance on the Coquihalla. The contractor, VSA Highways, says while cold weather was in the forecast there was no warning about freezing rain.

But they told CTV news that there's nothing you can do to protect a road at minus ten degrees when rain falls on it.

A recent poll of highway maintenance workers by their union showed that more than 39 per cent of them felt their employers weren't allocating the resources needed to properly do the job.

Transportation Minister Kevin Falcon denied CTV's request for an interview today. 

The RCMP say this accident is a vivid reminder of how conditions can change quickly at these elevations.

Everything's good when you're going straight ahead but as soon as you put the brakes on things can happen when its icy and that's exactly what's happened here," says Merritt RCMP Cpl. Mike Pears.

With reports from CTV British Columbia's Kent Molgat and The Canadian Press