The incident began around 1:30 p.m. Friday when suspect John Brigham was involved into a three-car crash, ABC News reported.
After the crash, witnesses told police Brigham began acting strangely, then he stripped down to just his socks and was "yelling and chanting."
Brigham then jumped on the roof of a car before carjacking a woman in a blue Toyota Prius, police said.
While in the Prius, Brigham caused two crashes, the second of which involved five other vehicles, KNXV-TV, Phoenix, reported.
During the second crash, Brigham was ejected from the car and proceeded to attempt to carjack other people, witnesses said.
Three people were injured during the first crash and four during the second, two of whom are in critical condition.
Brigham, who wasn't seriously injured, was arrested without resistance. He was transported to a local hospital.
Police said they are trying to determine why Brigham acted the way he did, but based on witness accounts, they believe his behavior may be linked to drugs or mental instability.