Misty conditions coupled with dropping temperatures created black ice that sent vehicles sliding on Highway 401 in the London-area on Friday morning.
Middlesex OPP were called to five collisions over a short time span including one that saw two transport trucks hit the concrete median in the eastbound lanes at Dorchester Road.
"If you are travelling please make sure you're aware that you may encounter black ice on our roadways," said Acting Sergeant Ed Sanchuk. "As the mist continues to fall it is turning into black ice in some areas. Reduce your speed and give yourself some distance between you and that other vehicle in front. Make sure you're checking your blind spots, signaling your turns and most importantly focusing 110 per cent on your driving ability and getting home to your families."
Slick conditions were also reported along Highway 402.
Black ice is considered incredibly dangerous as the thin coating blends into the pavement, making roads appear to be clear and dry when they are actually very slippery.