Most eastbound lanes have been reopened along a stretch of Highway 401 in Toronto, where two people were killed in a single-vehicle crash that impacted thousands on their morning commute.

Police say the crash happened shortly after 4 a.m. Wednesday morning in east Toronto, in the eastbound lanes near Warden Avenue. The SUV containing two occupants was travelling at high speed and the driver lost control, spinning out, rolling over and becoming airborne before striking the steel support for an overhead highway sign. Investigators say the roof of the vehicle struck the sign and the impact folded the vehicle in half, killing the occupants instantly.

Authorities were unable to remove the bodies at the scene, and spent several hours trying to move the vehicle before a crane was brought it. The SUV has since been taken to the Centre for Forensic Sciences, where the bodies will be removed.

Const. Prash Niranjan said investigators are looking at a variety of factors in the crash, including speed, road conditions, weather and traffic.

Police and the Ministry of Transportation of Ontario say they’ll look at the vehicle’s “black box” to see what more they can learn of the final seconds before the crash.

They’re also appealing for witnesses who may have seen the early-morning incident.

Most lanes were re-opened by noon on Wednesday, although the MTO lingered in the left lane to inspect the integrity of the overhead sign.