The bed of the pickup truck was holding construction equipment that ended up scattered across the intersection.
That debris caused two more vehicles to collide and one of those vehicles hit a bus that was parked at a bus stop.
A sixth vehicle was hit by a ladder that was in the back of the pickup truck, according to a witness.
"When we got hit on the left side of the bus the bus lifted off the ground," said Rebecca Machado, a bus passenger who saw another bus passenger get injured. "He was thrown off of his seat and came back and hit his head and his back I believe on the back of the seat and window."
That adult male passenger was also taken to a hospital.
Machado said there were five people on the bus and she was sitting directly across from the man who was injured.
"We got thrown into the poles so everybody was thrown out of their seats," Machado explained. "We saw the ladder coming straight at the windshield which made all of us kind of jump and try to figure out what was going on and then we felt the side of the bus get hit and we lifted off the ground."
Machado said her back is sore and she and the other passengers are shaken but otherwise, they are alright.
Phoenix firefighters evaluated a total of six patients at the scene.
The street was littered with debris including car parts, screws and other material.
It took street workers and tow truck operators about two hours to clear the scene.