While the investigation is ongoing, AZDPS is looking at weather as a contributing factor to the crash.

Earlier reports pegged the washout as a sinkhole, but Arizona Department of Transportation Spokesperson Ryan Harding said that flooding from the rain of Tropical Depression Rosa caused the 30-foot section of highway to sever.

A sinkhole is formed when a deposit of limestone dissolves from underground water, eroding it away over time. A washout happens when a large amount of water, like that of earlier this week, washes away the foundation of rock and dirt on which the road was built.

“The flooding, caused by the remnants of Rosa, cut through the highway and through the earth beneath it, necessitating extensive repairs,” Harding wrote in an email. “ADOT is currently evaluating the extent of the damage and will make short-term repairs to reopen the highway as soon as possible and return later with a project to make permanent repairs.”

While ADOT is working closely with tribal and federal partners to get the road open, US 89 is expected to remain closed for multiple days, he wrote, adding that there is no set timetable as to when it will be drivable again.