A Long Beach girl, 11, is dead following a fight with another 11-year-old after class outside a Long Beach elementary school.
Deputy Police Chief Robert Luna said the cause of Joanna Ramos' death outside Willard Elementary remained "undetermined," the LA Times reported.
Ramos died at a hospital hours after the fight on Friday, which authorities cited by the Associated Press said did not appear to be especially serious or violent, with no weapons were used and neither girl knocked to the ground.
The fight was planned in advance and lasted less than a minute, Luna reportedly said.
The Long Beach Press-Telegram quoted witnesses, Stephanie Guadalupe Soltero, who said she was friends with Ramos, as saying: "They were fighting over a boy. I told the teacher and she said she would talk to all the girls on Monday."
When Ramos returned to an afterschool program after the fight, adults noticed she wasn't feeling well.
Relatives took her home and later to a hospital, where she was placed in the Intensive Care Unit in critical condition.
Police are investigating and say no arrests are immediately planned.
The Press-Telegram quoted other witnesses as saying bullying had been a problem at the school.
Long Beach Mayor Bob Foster reportedly later said at a press briefing: "There are times when words do not convey the sense of sadness we feel."