LOS ANGELES – A teenager was charged Thursday with smuggling a gun onto a Southern California high school campus, where it discharged and wounded two classmates.

Two felony charges of bringing a firearm to a school zone and discharging it were filed by Los Angeles County prosecutors who also asked a court to try the 17-year-old suspect as an adult.

The teen, whose name was not released because of his age, could face up to nine months in a detention camp if convicted as a juvenile, and up to seven years in state prison if he is found guilty as an adult, county district attorney's spokeswoman Jane Robison said.

He remained in juvenile detention and was scheduled to be arraigned Friday in Long Beach Juvenile Court. Robison said she did not know whether he had obtained a lawyer.

Prosecutors said the teenager was on probation for a misdemeanor battery charge when he carried a loaded 9 mm Beretta semiautomatic handgun in his backpack to Gardena High School on Tuesday.

When he allegedly reached inside the backpack to get something to eat, the gun discharged a single bullet," according to a prosecution statement.

Earlier police reports had said the gun went off when the boy dropped the backpack on his desk.

The bullet struck a 15-year-old boy in the neck then hit a 15-year-old girl in the side of the head.

The girl remained in critical condition and was using a breathing tube on Thursday but she was showing improvement, said Dr. Gail Anderson Jr., chief medical officer at Harbor-UCLA Medical Center.

She "seems to be moving her extremities more. She's much more awake," he said.

The bullet didn't penetrate her brain, but it fractured her skull. She was treated for a blood clot and brain swelling, which included removing a piece of her skull temporarily to relieve pressure. She opened her eyes on Wednesday and Anderson said the swelling was reduced, although it was too early to determine whether she might have suffered permanent damage.

Children respond better, many times, than adults so we're hopeful," Anderson said. "But we really can't tell, probably, until she gets the breathing tube taken out. ... We're keeping our fingers crossed.

The bullet went through the boy's neck but missed major nerves, arteries and his spine, Anderson said. He was released from the hospital Wednesday to recover at home.

Authorities said that after the shooting, the 17-year-old fled the classroom and gave the backpack to a 15-year-old girl, and got different clothes from a 16-year-old boy. Both of those students were arrested on suspicion of helping the boy escape, but Robison said prosecutors have declined to file charges because of insufficient evidence.

Police have not discussed why the gun was taken to the school.

The school does not have permanent metal detectors. School district policy required staff to make random checks of students each day using hand-held metal-detector wands. However, district officials have said the school failed to perform the checks on the day of the shooting.