An 11-year-old girl is in a critical condition after a woman and three of her children were stabbed at a home in north London.
A 44-year-old man was arrested at the scene on suspicion of attempted murder following the "appalling attack" in Bounds Green, Enfield.
Police said the woman, in her 30s, and two girls, both aged under 12, are in a stable condition in hospital.
But a third child remains in a critical condition.
Police were called at 12:13 BST on Saturday to Livingstone Road, a residential street off the North Circular Road.
Officers said the attacker was known to the victims and they were not searching for anyone else.
Det Sgt Joe Stewart, of Enfield Criminal Investigation Department (CID), said: "This was an appalling attack on a woman and her young children.
"They have sustained very serious injuries. Our thoughts are with them as they continue to receive vital treatment in hospital.
"Attacks like this on such young people are extremely rare.
"The attacker was known to the victims. There is no further risk to the public at this time."
A crime scene and road closures remain in place around the area.
The man remains in a north London police station for questioning.