A teacher and a student have been shot dead and a second student critically wounded in a murder-suicide at a San Bernardino primary school.
A man opened fire with a pistol in a special education classroom at the Southern California primary school, fatally shooting the teacher and wounding the two students before killing himself.
Police said the student had died of his injures in hospital.
The gunman was the husband of the teacher shot dead, police say, adding that the wounded children were standing behind her.
Police said the two children were believed to have been caught in the gunfire unintentionally as bystanders to Monday's violence, which unfolded several kilometres from the scene of a December 2015 shooting rampage that killed 14 people.
San Bernardino Police Chief Jarrod Burguan said the shooting at North Park Elementary School in San Bernardino, east of Los Angeles, was an apparent murder-suicide.
Two wounded students were flown to a hospital where the 8-year-old later died.
"The children we do not believe were targeted," police Captain Ron Maass told reporters.
The 600 other students at the school were bused to safety at California State University's San Bernardino campus, several kilometres away. Television news footage showed students, escorted by police officers, walking off campus hand-in-hand.
As word of the shooting spread, panicked parents raced to the school, some in tears, some praying as they anxiously sought information about their children. They were told to go to a nearby high school where they would be reunited.
San Bernardino, a city of 216,000 people east of Los Angeles, was the site of a December 2015 terror attack that killed 14 people and wounded 22 others at a meeting of San Bernardino County employees.
Husband-and-wife shooters Syed Rizwan Farook and Tashfeen Malik were later killed in a gunbattle with authorities.