Interstate 10 eastbound was reopened at 5:19 a.m. on Sunday after being closed for more than 16 hours west of Phoenix after a horrific accident that took the lives of four people.

The Department of Public Safety originally told The Arizona Republic six people had died, but they confirmed Sunday morning that there were four deaths, two people in critical condition receiving life-saving treatment and six people taken to hospitals for their injuries. Five of those people had already been released.

The crash occurred shortly before 1 p.m. Saturday, according to a DPS spokesperson. The fiery crash happened about 14 miles west of Tonopah involving multiple vehicles and tractor-trailers, authorities said Saturday night.

Warren Trent, an agency spokesperson, said on Sunday morning that DPS would lead the investigation into the incident while noting that it would take time to fully reconstruct what happened given the number of people and collisions involved.

Trent said there was no evidence that speed or impairment were factors in the collision but that would ultimately be determined during the investigation. Adverse weather, however, might have played a role.

“Troopers are investigating whether blowing dust was a significant factor in the collisions by potentially causing reduced visibility,” Trent said.

He urged anyone driving in conditions where visibility was limited to slow down at the very least as it takes longer for a vehicle to come to a complete stop the faster it goes.

The Arizona Department of Transportation confirmed there is construction at that location.

Trent said the vehicles involved six commercial motor vehicles, four passenger vehicles, a van and a recreational vehicle towing a trailer.

Trent said DPS was not yet identifying any of the deceased as troopers were still working to notify next of kin.

“This is just a very tragic situation,” Trent said. “Very tragic.”

Trent said he didn’t know how long it took for troopers to respond to the scene, but there are troopers stationed across the state, so the crash’s remote location shouldn’t have been a factor.

A photo supplied by the agency showed several vehicles scorched by fire and intact tractor-trailers positioned along the freeway shoulder.

What caused the crash was not immediately known. Investigators worked at the scene late into the night.

Drivers heading east toward Phoenix were required to exit the freeway at milepost 81, Salome Road, creating huge backups throughout Saturday.

The accident occurred near milepost 88.

(This story was updated to add a video and new information.)