Two casualties have been airlifted to Alder Hey Children's Hospital in Liverpool after a car overturned on the A55 in rush-hour this morning.
The Welsh Ambulance Service also confirmed one patient has been transported by road to Ysbyty Gwynedd Hospital, Bangor.
The accident happened at around 8:30am and the A55 North Wales Expressway Westbound did not reopen until 11am.
The car reportedly overturned between J13 Abergwyngregyn Interchange and J12 Tal Y Bont Interchange.
There was no information on the condition of the three injured.
Social media posts shared locally show the Wales Air Ambulance helicopter at the scene, near a small silver car overturned on its roof, reportedly in the central reservation of the A55.
Fire, police and ambulance officers were also at the scene of the crash, with miles of traffic quickly building up as emergency services closed the road for two hours.
A separate road traffic accident took place at around 11:20am and involved three vehicles. North Wales Police said there were no reports of injuries.
The Eastbound carriageway of the A55 was closed again following the latest accident. Further delays are expected.