An arson probe has been launched after the door of a house was blown off its hinges when someone posted a lit firework through a letterbox.
Shell-shocked occupants, a young family, were in their front room at the time of the explosion at around 12.40am on Marsden Street, Accrington.
The firework wrecked the porch door and caused damage to the front door of the house.
Sergeant Steph Hurst, of Accrington Police, said the offender soon fled following the incident on Monday, February 18.
She added: "It's a nasty prank that could have been quite serious. The occupants have no idea why this has happened. It is bizarre. We are appealing for anyone with information to contact us on 101."