A woman was repeatedly stabbed in the lift of a housing block by a man who may have been lingering “around the block” for days.
The 41-year-old was taken to hospital with stab wounds to the chest and abdomen.
She remains in serious but stable condition.
The attack happened just before 15:00 BST on Thursday at Wimbourne Court, off Wimbourne and Shaftesbury Street, in Hoxton, east London.
Det Sgt Barry Hart, of the Metropolitan Police, said it was possible the suspect had been “hanging around the block both immediately before and in the days leading up to the stabbing”.
So far no arrests have been made and police are appealing for witnesses.
A police spokesman said it was not possible to say whether the victim was known to the attacker.