Four people are dead and two children are wounded after a gunman 'wearing green camouflage' targeted a US primary school and several other locations in a terrifying shooting spree.
The suspected gunman's deadly rampage was brought to an end when he was shot and killed by police.
Witnesses near the school in Rancho Tehama, northern California, said they heard up to 100 shots being fired after a truck drove through the school's gate.
Police and witnesses said the shooting spree began at a home before moving on to the school, where "multiple" victims were hit as shots were fired into classroom windows. A six-year-old girl was reportedly among the injured.
A man who says his roommate was killed by his neighbour described the suspect as "crazy", adding that he had been firing "a lot of bullets" recently and they had warned authorities.
Seven crime scenes were being analysed by detectives probing the latest mass shooting in the US.
Witness Coy Ferreira was dropping his daughter off at the school when he heard a pop that he thought was a firecracker.
He told KCRC TV that a school secretary ran out and shouted at children to get inside because someone was shooting.
Mr Ferreira said he ran into a classroom with 14 pupils and they hid as bullets came through the windows, hitting a boy in the foot and chest.
The boy was conscious and talking, and another student who was shot under the arm in an adjacent classroom was also conscious, he added.
The father said he saw a gunman - a man in his 30s or 40s - dressed in green camouflage running away from the scene.
Mr Ferreira believed there were two gunmen, although police had earlier said there was one.
A witness named Tiffany told KCRC TV that she heard 90 to 100 shots from the coffee shop she runs near the school.
She watched as a Honda car drove by with the windows shot out, and five ambulances soon raced to the scene.
Her husband Brian Rogers said another witness told him that they saw a white pickup truck drive through the school gate and someone start shooting.
A six-year-old girl was airlifted to hospital with two gunshot wounds, a second child was shot in the right leg and a 30-year-old man was shot in the right thigh, the Record Searchlight reported.
Local resident Brian Flint told reporters that his roommate was killed and the suspect was his neighbour.
He said: “I got a call that my roommate was injured and it was from a neighbour, and that there was an incident and a shooting and that my truck was stolen.
“The crazy thing is that the neighbour has been shooting a lot of bullets lately. Hundreds of rounds, large magazines.
"We made it aware that this guy has been crazy and he’s been threatening us and everything like that.”
He told Action News Now: "I just feel like maybe there should have been more effort into potentially stopping things like this."
Officers were called at about 8am local time after multiple shots were fired at a home.
They were then alerted to "multiple shots fired" and "multiple victims" at Rancho Tehama School, said Assistant Sheriff Phil Johnston of the Tehama County Sheriff's Office.
The suspected gunman was shot and killed by police, Mr Johnston told reporters at a police roadblock.
Mr Johnston said the school has been cleared and the children are in a "safe location".
He later told reporters that the gunman had killed four people before he was shot dead.
Local hospital officials said three people were transported by ground ambulances and one person was airlifted in a helicopter.
Three were children and one was an adult, Action News Now reported.
Before the suspect was located, police had urged local residents to stay in their homes.
The school was locked down until it was cleared by police.
Worried parents had gathered at a police roadblock while they waited for information on their children.
There has been nearly one mass shooting in the US every day in which at least four people were wounded or killed.
The Gun Violence Archive, which tracks gun crimes in the US, said there has been 316 mass shootings as of Tuesday, the 318th day of 2017.