Several vehicles including an 18-wheeler with two flat bed trailers were involved in an accident near I-10 eastbound and Buckeye Road on Wednesday morning.
The Department of Public Safety says a vehicle rolled over, blocking the HOV and three lanes.
A semi hauling mulch was involved and scattered its contents all over the freeway.
The driver of the semi, Jorge Pisceno, told FOX 10 a car leaving a crash on his left hit him and caused the semi to crash and flip.
"Crossed my line, one car close to me, I don't have time for brakes and lost control," said Pisceno.
The roadway was closed for the majority of the morning and cars were backed up for miles, even extending to I-17 and Arizona 51.
Southwest Farm services, who own the mulch on the crashed semi, brought in employees and equipment to help clean up the mess.
Three people were injured, including a woman who is seven months pregnant. She is expected to be ok.