A car has been deliberately reversed into a house many times, causing "substantial damage" to the living room.
No-one was inside the property in Reed Avenue, Great Harwood, when a grey Nissan Juke was driven into it at about 01:00 BST, Lancashire Police said.
Officers found the car had been "driven a significant way into the living room".
No-one has been arrested but police are appealing for anyone with information or footage to contact them.
A police spokesperson said work was "ongoing to understand the motivation for this attack", which was being treated as an isolated incident.
Det Insp Heather Martin added: "I understand that neighbours will be shocked and concerned by this incident and I want to reassure the Great Harwood community that we have a dedicated team of officers assigned to this case who are determined to identify those involved and bring them to justice."
