LA school shooting: Gun discharged single round from inside backpack, police say

LOS ANGELES, California -- The gun used in the Sal Castro Middle School shooting appears to have discharged a single round from inside a backpack, police tell ABC News.

Los Angeles police said according to the evidence, the gun appears to have fired one bullet from inside the backpack of the 12-year-old girl who was taken into custody in connection to the shooting.

Jory Rand reports the latest developments from a shooting at Sal Castro Middle School in the Westlake district on Thursday.

The bullet struck two students - a 15-year-old boy in the temple and a 15-year-old girl in the wrist. Investigators believe the trajectory of the bullet traveled through the wrist of the female student and then struck the head of the male student.

The handgun was not registered. Detectives are still trying to figure out where the girl got the gun.

She has been booked into juvenile hall Thursday night on on suspicion of negligently discharging a firearm on school grounds.

Investigators said they believe the shooting was accidental.

MORE: Sal Castro student calls brother, 'Someone just got shot, I need you'

A young man said he dropped everything and rushed to Sal Castro Middle School when his little sister called him and said, "Someone just got shot, I need you."

Doctors say the bullet that struck the boy in the head didn't hit anything vital and his injuries are not life-threatening.

Two other children and a staff member were hit by broken glass. All were expected to make a full recovery.