Four people have been hurt after a vehicle hit them while they were in their tents at a campsite.
A woman was critically injured and remains in hospital after the incident at Rhyd y Galen campsite, Caernarfon, in the early hours of Monday
Two men are in custody after they were arrested on suspicion of dangerous driving and drink-driving.
North Wales Police said: “This was a terrifying event for people who should have felt safe in their tents.”
It added that its thoughts were with the family of the woman who was seriously injured and were supporting those involved.
Another woman and two men were also hurt but have since been released from hospital.
Det Ch Insp Sion Williams said: “We are continuing to support those involved and we are asking anyone with any information relating to the incident to contact us.”