A blast of winter weather that included damaging winds and blowing snow caused chaos on highways in southern Ontario and left thousands of residents in several communities without power, authorities said Monday.One major crash took place on Highway 400 near Barrie, Ont., where several people were treated for minor injuries. Local fire officials said the collision involved more than 70 vehicles and required a stretch of the highway to be shut down in both directions.Ontario Provincial Police Sgt. Kerry Schmidt said the driving conditions in the area were terrible.“We have whiteout conditions right now — snow and blowing snow — we have zero visibility,” he said from the scene, where traffic was backed up in both directions.Videos of the collision posed by Schmidt online show dozens of vehicles, including several transport trucks and one fuel tanker, smashed together, with numerous cars also in the ditch.Barrie Fire public information officer Samantha Hoffman said the collision occurred around 10 a.m. on the southbound lanes of the highway. The crash had caused a 500-litre diesel spill that was under control, she said.“Crews have been called in to clean up the highway,” Hoffman said.Ryan Harris said he was driving south on the highway when he came upon stopped traffic that stretched out in front of him for about a kilometre.“Sometimes I can see the emergency vehicles, but there are moments where the wind is so strong that it’s just a complete whiteout and the truck starts shaking,” Harris said in a phone interview from his vehicle. “It’s really bad.”Authorities were also dealing with multi-vehicle pileups in other parts of the province on Monday.OPP Sgt. Jason Folz said there was a 20-car pileup on Highway 11 near Orillia, Ont., that occurred around 10 a.m. There were no serious injuries in that incident, he said. Several hours earlier, there was a 14-car crash on Highway 115 near Peterborough, Ont., again with no serious injuries, he said.“We’re recommending people stay off the roads today,” Folz said. “There are whiteout conditions happening all over the central region of Ontario.”High winds that swept across parts of the province late Sunday into Monday also left thousands without power. Hydro One said more than 160,000 people lost electricity in the nearly 24 hours since the storm hit. Spokeswoman Alicia Sayers said that while the utility has restored power to more than 130,000 customers, there are still hundreds of outages spanning from Windsor to the Ottawa area and as far north as Sudbury.Environment Canada said the wind storm was starting to die down from peaks registered late Sunday and into Monday morning, but gusty conditions and blowing snow continued to cause treacherous driving conditions in parts of the province.Spokesman Gerald Cheng said the winds are still significant even if they no longer meet the threshold for wind warnings in most cases.“It is starting to abate, but we’re not quite out of the woods,” Cheng said. “There’s still blowing snow issues across a large swath of the province.”Environment Canada’s current forecasts call for wind levels significantly lower than peak gusts of 128 kilometres an hour that were recorded on Sunday in Port Colborne, Ont., Cheng said.Video footage shot at the nearby Niagara River showed large chunks of ice spilling over a retaining wall and onto the shoreline, prompting Niagara Parks Police to close some roadways.Cheng said areas around Lake Huron and Georgian Bay are most likely to be affected by snowfall as the storm winds down on Monday, adding the wind warnings that have been cancelled across most of the province are still in effect in that region.Once the wind has died down completely, Cheng said deep cold is expected to set in across another large swath of the province.Extreme cold alerts are expected for much of northern Ontario in the coming days, Cheng said.Further south, cities like Toronto can expect temperatures to dip below -15 degrees Celsius with wind chill values making conditions feel colder, he said.