Four people, believed to be in their teens, from the Cross maglen area of Co Armagh have received hospital treatment on both sides of the Border after the car they were travelling in left the road near Cullaville village, Co Armagh.
It is thought the vehicle crashed through a hedge and overturned in a field off the main Dundalk to Castleblayney Road.
Emergency services from both sides of the Border attended the scene.
Three of the car's occupants were reportedly later released from hospital, while the fourth was detained. His condition is not known.