A serious accident caused major delays on Interstate 17 in Phoenix on Wednesday.
Bart Graves with the Arizona Department of Public Safety said the wreck involved six vehicles, one of which was a semi-truck carrying diesel fuel.
"Apparently a truck made an evasive move in traffic after the driver of another truck hit the gas pedal prematurely, which caused it to slam into a number of other vehicles," he said.
Four people were hospitalized with serious injuries, but all are expected to recover.
Graves said the truck has leaked 100 gallons of fuel.
As a result of the accident, all northbound I-17 lanes at the I-17/I-10 interchange near Phoenix Sky Harbor were closed. Traffic was detoured along the I-10 inner loop, where they can reconnect to I-17.
The closed lanes were reopened about 3:45 p.m.