A 15-year-old girl is critically ill after a bullet grazed her skull during what is thought to have been an accidental shooting at a school in Los Angeles.
Another student, a boy aged 15, is said to be in a "fair" condition with a neck wound after a gun in a fellow 10th-grader's backpack discharged at Gardena High School.
Both teenagers were hit with the same bullet, Los Angeles deputy police chief Patrick Gannon confirmed.
John Deasy, deputy superintendent of the Los Angeles Unified School District, said there was no indication the student with the backpack had touched the gun before it discharged.
"He literally dropped his knapsack on the desk and it went off," Mr Deasy said.
Mr Gannon added: "He said, 'I'm sorry,' when the gun went off. It made it appear to the teacher that it was an accident."
The unidentified student has been arrested and charges are pending.
The 15-year-old girl suffered a skull fracture and bruising to the brain and developed a significant blood clot. The blood clot was removed successfully, but the girl remains sedated and in critical condition at Los Angeles County Harbor-UCLA Medical Center, with her family was by her side.
A 15-year-old boy was in fair condition after being shot in the neck in a classroom at Gardena High School, a sprawling, 1950s-era school with rows of barracks-like classrooms.
The shooting occurred in a classroom at the school, where Principal Rudy Mendoza said students were on a break at the time. The campus was locked down after the incident. Police initially reported a shooter was at large.