A doorman at a Beijing kindergarten has stabbed 15 children, killing one of them, according to Chinese state media.
The attacker stabbed the children with a kitchen knife
Three teachers were also injured when the knife-wielding man went on the rampage at a nursery in Beijing University's Number One Hospital.
The alleged attacker, 51-year-old Xu Heping, has now been detained by police for questioning.
The motive for the stabbing is unclear, but Mr Xu is said to have had a history of mental illness.
The incident was "the worst attack on children in the capital in decades", according to China
Central Television (CCTV).
Early on Wednesday morning, police received an emergency call saying that a man had been "hacking people up at the kindergarten" with a kitchen knife, according to the website sina.com.
Eight officers went to the scene, where they soon overpowered and arrested the man, the website said.
A four-year-old boy died due to serious injuries and blood loss.
Two other children and a teacher sustained serious neck wounds, and are in a critical condition, according to Xinhua news agency.
The other victims were said to be "covered in blood", but their injuries were not thought to be life-threatening.
"It was too cruel, it happened in a moment or so. The
victims were just kids and I saw the bodies dangling inside the
emergency cars," one woman told CCTV.
Another witness told the Associated Press news agency: "Blood was everywhere. The kids were lying on the ground."
Police and city officials said Mr Xu had a history of schizophrenia.
"Due to illness, Xu Heping was hospitalised at the Beijing Anding Hospital for treatment from 11 May to 24 September 1999,"
the Beijing government information office said in a faxed
Violent crime used to be very unusual in China.
But in recent years, there have been a series of horrific attacks. In February this year Yang Xinhai was executed after being found guilty of 67 murders spread over a three year period.
In June, university student Ma Jiajue was also executed after being convicted of killing four classmates and stuffing their bodies into a cupboard.
Attacks on young children have also shocked China in recent years.
In one of the worst incidents, in 2002, police detained a kindergarten doctor after he confessed to putting rat poison in salt at a rival nursery, where 70 children and two teachers had fallen seriously ill.