Police are investigating a violent crash on the Sea to Sky Highway that left two people dead and several others injured on Tuesday night.

Authorities said a northbound pickup truck crossed the centre line just outside Squamish at around 7:30 p.m. and collided with a southbound minivan that was carrying seven people.

The driver of the minivan and one passenger died at the scene. The other five passengers suffered injuries ranging from minor to life-threatening, and one remained in hospital Wednesday afternoon in critical condition.

The pickup truck driver was seriously hurt as well, but is expected to survive.

Witnesses said dozens of people stopped at the accident scene and tried to lend a hand, including Stephen Wright, who returned to the scene the next day to lay flowers.

Wright, who applied his first aid training before paramedics arrived, said witnessing the aftermath of the crash was a deeply affecting experience.

"We connected with some of the gentlemen who were conscious and stabilized them," Wright said. "We stayed with them several hours."

The names of the deceased are not being made public, police said, but their next of kin has been notified.

Six ambulances and two helicopters ultimately responded to the accident, which forced authorities to close the Sea to Sky for several hours and left many drivers stranded in their cars.

Jacob Freese, owner of Fergie's Café, opened his doors to give some of the displaced travellers a place to stay until the highway reopened at around 2:30 a.m.

"I've been trapped in that traffic before," Freese said. "We thought about what we might want, and hot fire and a cup of coffee sounded like the best idea."

It's unclear what caused the pickup to cross into oncoming traffic; police said they could not speak to road conditions on Wednesday.

"I don't know what the road conditions were like specifically last evening, but I know… [they] can change with very little warning because of changes in elevation and things like that," said Const. Mike Halskov.

"Drivers need to be reminded to just take it easy, make sure your vehicle is equipped with proper winter tires, and to drive according to the conditions."

The RCMP's Sea to Sky Traffic Services and the Integrated Collision Analysis and Reconstruction Services are continuing to investigate the crash.

With files from CTV Vancouver's Nafeesa Karim