Surveillance video of 15-year-old Peter Montenegro was taken shortly after the attack.
Investigators say Montenegro shot Amarjit Kuar during a failed robbery attempt.
Kuar is recovering.
Vallejo police say they tracked Montenegro down on Wednesday night in Oakland.
He was arrested on Hegenberger Road near I-880.
Montenegro is being questioned at Alameda County juvenile hall.
A 14-year-old accused of being his accomplice was arrested last Friday.