A teenage boy and his baby sister were abandoned at the side of a road after their mother's car was stolen from a filling station in Warrenpoint.
Their mother had gone into the shop on the Newry Road shortly after 2130 GMT last Thursday before a man thought to be in his 20s stole the vehicle.
The children - aged 14 and seven months - were found unharmed a short time later at the side of Narrow Water Road.
The stolen BMW car was found in the Dundalk area on Friday.
A member of the public brought the children back to the shop where they were reunited with their mother.
Police are appealing for anyone who may have been in the area at the time and witnessed the incident.
They especially want to speak to anyone who was at the filling station and noticed a blue Vauxhall Vectra car with a number of men on board at about 2130 GMT last Thursday.