Police received a call shortly after 3:30 p.m. reporting six people fighting in the parking lot of the Safeway supermarket at 3334 Alhambra Ave.
Moments later, police received a second call reporting that a teenager had been stabbed and the assailants were running away.
When officers arrived, they found the victim in the parking lot. He had been stabbed once just below his right eye and was transported to a hospital for treatment, police said.
Meanwhile, other officers quickly located a group of people matching the description of those who had been involved in the fight and detained them.
A 15-year-old boy was identified as the person who allegedly stabbed the victim. He was booked into juvenile hall in Martinez on suspicion of assault with a deadly weapon.