A father stabbed his three young sons to death in the back seat of their car outside a South Los Angeles school, US police have said.
The father, said to be in his thirties, was found in his car bleeding from stab wounds to the chest, with his dead sons in the back and a knife in the passenger seat.
The boys, aged between eight and 12, were pronounced dead at the scene. It is thought the father turned the blade upon himself after killing the three boys.
The father, whose name has not been released, is the only suspect in the killings, police said. He was taken to a hospital in critical condition and will be arrested if he survives his wounds, Los Angeles police officer Matthew Ludwig said.
The motive was unclear and is being investigated. The father had no history of domestic violence charges or arrests, police said.
"These are horrific incidents," police chief Charlie Beck said. "These are incidents that have scarred not only a community but the first responders that have to handle them."
"It is a sad day in LA."
The three boys did not attend the elementary school next to the crime scene, Mr Beck said, but they are enrolled in the Los Angeles Unified School District.
Mr Beck said the boys' mother is deceased and that their stepmother was safe and being interviewed by detectives.
It is unclear whether the boys lived with their father.
The deaths come as homicides are on the rise in Los Angeles. In August, 39 killings drove a year-to-date rise in murders in the nation's second-largest city, according to police statistics. The 39 killings in August are compared with 22 the previous month and 19 last August.