Girl beaten to death in US school bathroom 'over a boy'

A US teen is dead after being beaten up by bullies in a girl's bathroom in a fight over a boy.

Amy Joyner-Francis, 16, was attacked just before classes started at Howard High School in Wilmington, Delaware, on Thursday morning, local media reports.

She apparently told two friends the night before she was going to have to "settle the beef" with other girls at her school, the fight reportedly being over a boy.

Friend Nik Stryminski said Amy was known as a peacemaker, having defused a situation involving him shortly after he started at the school.

“It’s not even like she went in there to fight. She went in there to talk things out,” Mr Stryminski said.

"She didn’t believe in fighting, and the craziest thing is she died in a fight.'

Other witnesses deny the fight was over a boy, but have refused to say what caused it.

Police believe she was first attacked by another student, and then others joined in.

At one point her head was banged against the bathroom sink, police believe.

She was airlifted to hospital but died shortly after arriving.

Her cause of death is still unknown.

Three girls have been questioned by police.

"Now they know they're in very serious trouble and could spend a substantial amount of time in prison," Mayor Dennis Williams told CBS News.

Charges are expected to be laid next week, after the autopsy report has been completed.