A 49-year-old man has been arrested on suspicion of drink-driving after a crash left four people hurt, one seriously.
He was also detained suspected of fleeing the scene of the three-car crash on the A4244, near Brynrefail, Gwynedd.
North Wales Police said the incident happened at about 15:00 BST on Sunday.
Both drivers and passengers of a Mazda MX5 and Nissan Duke were taken to Ysbyty Gwynedd hospital in Bangor.
The Nissan's driver was later transferred to hospital in Stoke with serious injuries, after the crash that also involved a VW Golf.
Sgt Raymond Williams of the roads' policing unit said: "We arrested a local male shortly after this collision, on suspicion of driving whilst over the prescribed limit of alcohol, dangerous driving, failing to stop after a collision and failure to stop for police.
"I believe the vehicle had travelled from the Bethesda area.
"Anybody who may have been travelling on that road between 2.30pm and 3pm (on Sunday) and who saw a black VW Golf being driven in a dangerous manner to contact us," he added.