A woman suffered serious head injuries after a man she knew attacked her with a "bladed object", police said.
The 50-year-old victim was hit several times on the head before she fled the attacker outside a home in Caversham, Berkshire, at 16:30 GMT on Wednesday.
Thames Valley Police said she remains in hospital in a stable condition and they are treating the case as attempted murder.
No arrests have been made at this stage.
Officers said the attacker is a a white man aged in his 20s, with short brown hair.
Det Insp Dave Turton said the force believed the attack was an "isolated incident", but there was a "good chance that a number of people witnessed it".
"People in the area might see an increased police presence while our investigation takes place," he added.