Two men and two women have been injured after a car crashed through tents at a campsite near Caernarfon.
One of the women remains in a "critical condition" in hospital.
North Wales Police said it was, "a terrifying event for people who should have felt safe in their tents".
Police are investigating the incident which happened in the early hours of Monday morning on the Rhyd y Galen campsite.
Two men have been arrested on suspicion of dangerous driving and driving with excess alcohol. They are still in custody.
North Wales Fire and Rescue Service said two fire engines were sent to the campsite.