The shooting occurred around 8am local time, with police responding to reports of shots being fired at the Berrendo middle school.
It’s thought three students have sustained injuries in the attack.
A 14-year-old boy is reported to be in a critical condition, while a 13-year-old girl has been taken to hospital to be treated for gunshot wounds.
A third person is claimed to have been caught up in the gunfire, but details of their condition have yet to be released.
It's now being claimed the suspect being held in connection with the shooting is a 13-year-old student who attended the school.
According to eyewitnesses, the shooting occurred in the school gym.
The suspect is alleged to have opened fire, hitting the 14-year-old boy in the face before shooting the 13-year-old girl in the arm.
He was then tackled by a teacher who managed to stop him firing off more rounds.
Frantic parents - who were notified by phone call - gathered outside the school buildings before they were moved to a local shopping mall to collect their children, after the students were bussed away from the scene.
Reporters outside the school have been talking to parents about the horror of the situation, with one mother telling one news station, "I just want my babies. I want to put them in my arms and hold them. That's all."
A press conference is set to be held in the coming hours.
We will keep you updated on this as the situation develops.