The attack happened at about 1:17 p.m. Thursday across from the school. The victim, who friends identify as Zachary Estrada, was airlifted to an area hospital after he was hit in the head with a hammer. Estrada was listed in critical condition Friday.
Chino residents Gregory Richmond, 48, and wife Raina Crawford, 40, were both arrested for attempted murder. Police said they live in an apartment adjacent to the scene of the attack. Richmond and Crawford were held on $1 million bail each, and arraignment was scheduled for Jan. 21.
Police did not release details of the attack. It was unknown if the suspects and the victim knew each other.
Chino High School classes were not in session at the time of the incident because of early dismissal, but the school and nearby Walnut Elementary were locked down until the arrests were made.