The OPP have confirmed that there were multiple fatalities after a serious collision Tuesday night involving 14 vehicles on Highway 400 in the Newmarket.

Sergeant Kerry Schmidt says all lanes of the 400 are closed between Country Road 88 and Highway 89 after the crash, which also involved two fuel tanker trucks.

Video footage of the scene posted on social media shows towering flames and the sound of loud bangs.

One witness says flames were shooting 100 feet into the air.

The number of people who have been killed is still unclear at this time.

Schmidt says the highway closure may last all day today.

The original crashes happened around 11:30 pm.