Strong winds, low visibility from blowing dust, and human error likely contributed to a 19-vehicle pileup on Interstate 10 on Tuesday that killed three people and injured a dozen more between Phoenix and Casa Grande, authorities said.
Included in wreckage near Picacho Peak were 10 commercial vehicles, one tanker, one recreational vehicle and seven passenger vehicles, according to the Arizona Department of Public Safety.
At least six semitractor trailers were involved in the pileup at about 12:30 p.m. Multiple passenger vehicles were severely damaged, some wedged among the trucks. The entire cab of one truck was crushed, and at least one passenger vehicle appeared to be lodged under a trailer.
George Lee Smith, 77, of Mead, Wash., was the first of three killed in the collision to be identified by the DPS. Officials said Smith's wife was injured and was receiving medical treatment.
More than a dozen people were hurt, the severity of their injuries ranging from serious to life-threatening, according to Bart Graves, a DPS spokesman.
Remnants of the collisions continued to block westbound lanes of the interstate well into Tuesday evening. At one point, westbound traffic was backed up 10 to 15 miles, while eastbound lanes were stalled 5 to 6 miles deep.
It was not immediately clear what sparked the pileup, but Graves said human error is typically a factor. Authorities are investigating.
The National Weather Service issued a short-term forecast of blowing dust before the crash, followed by a dust-storm warning shortly after the collision occurred, said Marvin Percha, a Weather Service official in Phoenix.
"They just happened to be in a channel where dust picked up easily," Percha said.
A study released earlier this year by National Weather Service identified the I-10 corridor near Picacho Peak as one of the deadliest in Arizona for dust-related collisions. The study referenced crash data compiled by the Arizona Department of Transportation from 2001 through 2011.
ADOT cautions motorists to stay alert during dust storms, where visibility can suddenly drop to zero. In the event of a dust storm, motorists are encouraged to slow down, pull off the roadway and turn off all vehicle lights.
Arizona Republic reporter Kirsten Kraklio contributed to this article.