Updated at 11 p.m. ET

Two students were hospitalized with gunshot wounds in Los Angeles after what police describe as an accidental shooting Thursday morning at Salvador Castro Middle School. A 12-year-old girl has been arrested.

Late Thursday, The Associated Press reported:

"[Police] spokesman Josh Rubenstein says the 12-year-old girl arrested in Thursday's shooting was being booked on a charge of negligent discharge of a firearm on school grounds.

"Twelve-year-old Jordan Valenzuela, a classmate, tells The Associated Press that he talked to her just after the shooting.

"He says she was sobbing and kept repeating, 'I didn't mean it.' He says she told him that the gun was in her backpack and that it accidentally went off when she dropped the bag."

Both students who were shot are 15 years old — a boy who is in critical condition with a gunshot wound to the head and a girl who was shot in the wrist and is in fair condition. Erik Scott of the Los Angeles Fire Department said three other people, ranging in age from 11 to 30, "suffered abrasions" during the attack.

The 15-year-old boy is expected to fully recover. Trauma surgeon Aaron Strumwasser said the victim was lucky the bullet that struck him in the temple did not cause life-threatening damage. "I think he will do fine," said Strumwasser at the LA County-USC Medical Center, as quoted by the Los Angeles Times.

"As a parent, this is everyone's worst-case nightmare — a worst-case scenario and a nightmare for all of us," Robert Arcos, commanding officer of the Los Angeles Police Department's Operations-Central Bureau, told reporters Thursday.

He said at the time it was too early know how the girl obtained the weapon.

As AP explains, district policy dictates that "students at middle and high schools in Los Angeles are subject to daily random searches for weapons using metal-detector wands, but officials have not said whether any such screenings occurred at the school Thursday."

The Los Angeles Times notes Castro Middle School sits just across the street from Belmont High School, in a building that "used to be part of Belmont High when the high school had a higher enrollment."

"I'm just scared for all the kids," Gloria Echeverria, mother of a 13-year-old student, told the AP while standing outside the police tape ringing the campus. "School is supposed to be a safe place for them, and apparently it's not."

At least a dozen school shootings have occurred already in 2018.

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