Investigators on Friday were trying to determine why a gunman opened fire on vehicles and pedestrians for some 90 minutes across metropolitan Phoenix, leaving one person dead and a dozen others injured in the string of drive-by shootings.

Authorities believe a man they arrested after the shootings on Thursday acted alone. His identity hasn't been released.

There were at least eight separate shootings in three cities, stoking fear throughout the region and shutting down parts of major freeways as police gathered evidence. Four people were shot, including the person who died.

Others were injured as bullets shattered glass or as their vehicles crashed. Authorities said the injured victims were all adults and expected to fully recover.

Neil Betrue, a pastor in the city of Surprise, was alone in his church's office when he noticed a few police officers and heard a helicopter buzzing overhead. He peered out the door and saw a swarm of police surrounding the suspect's car and started recording the commotion on his cell phone.

“I did not know at the time it was a shooting spree happening,” Betrue told The Associated Press on Friday. “I just thought maybe there must have been a car chase or something.”

Richard Valencia said he spent Thursday afternoon in the hospital after being shot in the shoulder as he walked from a convenience store in the city of Surprise. The 34-year-old told Phoenix news station KSAZ-TV that he fired back three times with his own weapon.

“I don’t even know the guy,” he said. “It was completely random.”

Another victim was able to give authorities a description of the suspect's vehicle — a white Volkswagen SUV — and the license plate number. A local fire department spotted the vehicle and called police, who swarmed a shopping center that includes restaurants, a nail salon and a Walgreens.

As officers drew their weapons, the suspect, wearing a black jacket, black pants and white shoes, raised his hands in the air. He then was cuffed without incident, Betrue's video shows.

“I'm just thankful that he didn't ty to put the officers or any of the business or anyone else in harm's way here,” Betrue said.

Police don't believe anyone else was involved in the attacks.

“We don’t know the nexus, we don't know what the motive was," said Brandon Sheffert, a spokesman for police in the city of Peoria. “We don't have an idea of what this person was thinking when he went out and did this.”