The RUC was last night questioning three youths after a woman and her young son were knocked down and killed by a stolen car in Belfast.
Meanwhile in the Republic, four people died in road accidents over the weekend, bringing to 401 the number killed on the State's roads this year.
In Belfast, one youth was arrested close to the scene of the fatal accident, on the Antrim Road in north Belfast. Two others were arrested in Ardglass, Co Down. Ms Dana Fitzpatrick (28) and her son Kevin (8) were killed when a car struck them at high speed as they stepped onto the road on Saturday night.
The car, stolen five minutes earlier in the city centre, then crashed into another vehicle. Three people were believed to be inside the stolen car and all ran off.
Meanwhile, a man was killed and three others injured in a car crash in the Shankill area of Belfast on Saturday. Mr Robert Armstrong (19) died when the vehicle hit a lamp-post on the Woodvale Road.
In Co Laois, two men in their 20s died after a head-on collision between a lorry and a car at Castletown, near Portlaoise, early on Saturday morning. The crash happened shortly before 6 a.m. and the car driver and his passenger died. They were Mr Brian Maher (22), from Castletown, and Mr Kevin Moore (26), from Borris-in-Ossary.
Also on Saturday, a 23-yearold Latvian died after being struck by a car and then by a truck as he walked with a friend at Bangup Cross, Ballan, Co Carlow. The accident happened at 7.45 p.m when the two men were struck by a car.
The man, whose name is not being released until his relatives have been informed, was subsequently hit by a truck. The second pedestrian, also a Latvian, was not seriously injured.
In Co Waterford, a 60-yearold man died after a head-on collision between two cars at Toortane, Lismore. The accident happened on the road between Tallow and Lismore. The body of a 40-year-old man who was killed near Swinford, Co Mayo, on Friday, when his car went out of control and struck a wall, was returned to his native Sudan at the weekend.
Elrashid Malik, a doctor at the Mayo General Hospital, Castlebar, was married with two children. His wife and family were due to join him in Castlebar shortly.
An inquest was conducted so the body could be repatriated. Evidence was given that Mr Malik's car veered out of control while overtaking. An inquest jury returned a verdict of accidental death.