(Image Credit: ABC News)

Police in Scottsdale, Ariz., are trying to figure out what caused a 45-year-old man to go on a naked carjacking spree that left seven people injured, caused several crashes and shut down nearby roads.

Around 1:30 p.m. on Friday, the suspect, John Brigham, was involved into a three-car crash, police said. After Brigham got out of his car, witnesses said he began engaging in bizarre behavior.

He took off all of this clothes, with the exception of his socks and was "yelling and chanting," witnesses told police. Brigham jumped onto the roof of another car before carjacking a woman in a blue Prius, leaving the scene of the first accident.

A short time later, investigators said, Brigham allegedly caused a second crash involving five cars.

The wife of a man involved in the crash said Brigham was undeterred and tried to carjack other vehicles, despite the fact he had been ejected from the Prius at impact.

"He got out naked running all over the place trying to get into other people's cars," the unidentified woman told ABC News' Phoenix affiliate. "When he called and said he was hit by a naked man in a Prius, I thought it had to be a joke."

Four people were injured in the second crash, including a pregnant woman who broke both her legs, police said.

Brigham was arrested and taken to the hospital for observation. He could face carjacking and felony hit-and-run charges.