Adverse weather is set to continue around the country with the worst of the conditions expected to affect the north and north-west.
The North's Roads Service is braced for further snowfalls and a repeat of the conditions which caused havoc across northern counties yesterday .
Up to six inches (15 cm) of snow fell in the early hours of yesterday, with Tyrone and Fermanagh worst affected. The snowfalls caused traffic and travel disruption and the closure of dozens of schools.
In Co Antrim, five children were hurt when a car veered off the road and struck them. The five, aged between 11 and 17, were waiting for their school bus near Lisburn at around 8.30 a.m. when the accident occurred. Two were treated for minor injuries at the scene by a local doctor. Three others were taken to hospital with suspected head injuries.
There were severe holdups with some main roads badly affected. These included the Belfast-Derry road at the Glenshane Pass which rises to more than 1,000ft (300m), and the Coleraine-Limavady road in Co Derry.
The M1 into Belfast was also badly affected, and tailbacks caused by a road-widening scheme were more severe than normal yesterday morning.
There were minor accidents on secondary roads, some of which had not been treated. The Roads Service said it had gritted 4,300 miles of roads overnight using up to three times the normal amount of salt. However, a spokesman claimed that grit on its own was of no use until vehicle tyres had acted on it, causing snow to melt.
Translink, which operates public transport in Northern Ireland, reported delays on all services and advised travellers to expect travel times to be exceeded by at least 15 minutes.
Flights in and out of Belfast's two airports were also delayed, and some services to the Isle of Man were cancelled. Dozens of schools were closed and some have already announced there will be no classes today.
The Met Office at Aldergrove, Co Antrim, said the cold conditions were expected to continue for a couple of days, but snow showers were expected to die out. Elsewhere cold and icy stretches are expected with scattered snow showers. Some eight centimetres of snow were recorded at Knock Airport yesterday. However, heavy snowfall is not expected to affect the rest of the country.
AA Roadwatch has advised drivers to take extra precautions, particularly in the north-west, as below-freezing temperatures will have caused icy patches. While most of the snow will affect Ulster, a bitterly cold northerly wind will take some snow showers around the country. These will die out over Leinster and Munster during the day.