Two teenage students have been shot at a Los Angeles school, and police say that a 12-year-old girl is in custody and her weapon has been seized.
The gunfire broke out at 08:55 local time (16:55 GMT) at Salvador Castro Middle School in the Westlake District.
A 15-year-old boy who was shot in the head is in "critical but stable" condition, and a girl, 15, was shot in the wrist, officials say.
Three others, aged 11 to 30, suffered minor injuries, police say.
The Los Angeles Police Department (LAPD) confirmed to the BBC the female is 12 years old.
A spokesman for the LAPD tells BBC Los Angeles correspondent James Cook that police do not believe this is an ongoing threat, but added that police are still searching the area to check for any additional victims or weapons.
The school will remain on lockdown for the remainder of the day, officials added.
#LAPD 15yr old boy was shot in the head, he is in stable but critical condition. 15yr girl shot in the wrist, she is in fair condition.— LAPD HQ (@LAPDHQ) February 1, 2018
An 11-year-old boy, a 12-year-old girl and a 30-year-old woman reportedly sustained minor injuries, with abrasions to the head and face but were not shot, said Fire Department Captain Erick Scott at a news conference.
Authorities have not released a suspected motive for the shooting, or more details of how the girl was arrested.
Steve Zipperman, the chief of police for Los Angeles schools, said that investigators will carefully examine the case and will make trauma counsellors available to any students who may need them.
"We will attend to the needs of these students who witnessed this very carefully, with the understanding that this is very traumatic," he said at a press conference outside the school.
Interim Superintendent for the Los Angeles Unified School District Vivian Ekchian said in a statement, "our thoughts and prayers are with those who were hurt in today's shooting incident".
Ms Ekchian added the school district is "providing appropriate supports to those who may be impacted by the incident".
This is at least the third shooting at a US school in recent weeks.
On 23 January a student in Kentucky opened fire on fellow students, shooting 17 and killing two.
A day earlier, a 16-year-old student was apprehended after wounding a student at a Texas school.