A man has suffered serious facial burns in a suspected acid attack in Liverpool.
Officers were called to the victim's house in Wavertree on Tuesday night and found the 33-year-old with burns to his face and neck.
A police officer who took him into the house to get cold running water on his injuries also suffered burns to his hands and arms.
Police believe it was a targeted attack and say one man has been arrested.
Det Ch Insp Kath Adams, leading the investigation, said: "This was an extremely nasty incident which has left a man with burn injuries to his face, neck and body.
"At this stage of the investigation we believe that a substance has been thrown in his face as he has opened his front door.
"Fortunately the emergency services turned up very quickly and the first police officer on the scene was able to get this man under a cold shower to wash off as much of this substance as possible."
The victim remains in hospital but the officer, Pc Barry Norton, was discharged and has since returned to duty. His actions have been praised by senior officers.
A 39-year-old man, from the Toxteth area, has been arrested in connection with the investigation and remains in police custody.