A 12-year old girl has been held in custody in Los Angeles in connection with a shooting at a school that left several people injured.

The incident, which is thought to have been unintentional, happened at Salvador Castro Middle School in the city.

According to reports, the gun is believed to have been in a backpack and accidentally went off when the girl dropped the bag.

A 15-year-old boy was shot in the head, and police initially said he was in a 'stable but critical condition'. However, local media later quoted doctors as saying the teenager was expected to make a full recovery.

Another student - a 15-year-old girl - was said to be in a 'fair condition' after being shot in the wrist.

Three other people - including two students - are thought to be have suffered minor injuries.

In a statement quoted by the Los Angeles Times, the LAPD said: "At this time, the information suggests that this was an isolated incident, involving the negligent discharge of a firearm, where innocent children and a staff member were unfortunately injured".

A handgun is also reported to have been recovered at the scene.

LA Mayor Eric Garcetti, meanwhile, said in a statement: "I am praying for the students shot today at Sal Castro Middle School, and want to express my deepest gratitude to the faculty and first responders whose quick, courageous action prevented this tragedy from becoming far worse.

"We should all be beyond outraged by the terror that a needless proliferation of guns can bring into our children’s lives without warning or cause."