An 11-year-old girl and her mother are in a critical but stable condition after being found with stab wounds in west London.
A Metropolitan Police spokesman said officers were called to Durdans Park on Lady Margaret Road in Southall at 1430 BST on Saturday.
The woman, aged 47, and child were airlifted to hospital.
A police spokesman said they were not looking for anyone in connection with the stabbings.
The pair were injured in a park across the road from the family home, neighbours said.
The alarm was raised after a Polish dog walker found the pair, one neighbour added.
The 46-year-old man, who lives nearby but did not want to be named, said: "There was no-one else about, we are told, apart from the Polish man."
Two police tents have been erected on a patch of grass behind the street as forensic officers continue to check the area.