PHOENIX (AP) – Dozens of vehicles collided in heavy, blinding snow on a northern Arizona interstate Sunday, killing two people, seriously injuring 10 others and forcing police to close the highway for 20 miles in both directions.

The low visibility on Interstate 40 near Flagstaff caused about 20 collisions, which occurred over a stretch of highway at least 4 miles long around noon, Flagstaff Fire Department Chief Mark Wilson said.

He described the wrecks as clumps of vehicles piled on top of each other, involving cars, trucks and semis.

“The magnitude of it was pretty severe,” Wilson said.

“We had a whiteout scene with the snow, and obviously a single-vehicle accident caused multiple-vehicle accidents, which continued to pile up due to the low visibility.”

Wilson said two people died, and 15 people had to be removed from vehicles with hydraulic equipment and hand tools.

Flagstaff Medical Center spokeswoman Starla Addair said the hospital received 53 patients, at least 10 of whom needed to be admitted for serious injuries. She said 35 patients were treated and released.

Red Cross volunteer Gene Munger said about 40 people involved in the wrecks were at a middle school shelter Sunday evening deciding whether to spend the night there on cots or find a hotel.

“They’re pretty shook up right now,” he said.

National Weather Service meteorologist Clair Ketchum said whiteout conditions occurred off-and-on Sunday afternoon in the Flagstaff area and could occur overnight as a storm rolls across the state.

Ketchum said 3.8 inches of snow fell by 5 p.m. Sunday near where the collisions occurred.