National Emergency Coordination Group say dangers still exist even after Storm Ophelia has passed
"There will be dangers even after the wind has passed"
A serious threat to life still exists despite the worst of Hurricane Ophelia having passed.
Hundreds of roads will remain impassable overnight and 330,000 homes are without electricity.
However, Met Eireann's Evelyn Cusack said the "exceptional severe winds are over".
The most violent winds were recorded at Fastnet Lightnouse (191 km/h), Roches Point (156km/h) and Kinsale Platform (141km/h). Winds at Dublin Airport Peaked at 104km/h.
Following a National Emergency Coordination Group, its chairman Sean Hogan said: "There will be dangers even after the wind has passed.
"Unfortunately this storm has left tragedy in its wake and we expend our sympathies to these families."
He said the "next stage is now underway" and clean up crews are already on the ground in parts of the country.
Mr Hogan said the decision to effectively close down the country for the day by issuing a red alert weather warning was taken "based on the best scientific advice".
He said Met Eireann has entered "unchartered territory" but the emergency group was in no doubt that it was the correct decision.
ESB Networks has warned that it could be up to eight days before power is restored to all homes.
Assistance is to be flown in from England and Scotland on Wednesday to help with the massive power outages.
Derek Hynes of ESB said there are "significant public safety hazards" around the country.
He urged people not to cut timber in a bid to clear lines - but to instead contact ESB for expert help.
The company will prioritise vulnerable customers such as nursing homes and medical facilities.
"People should not take any risks over the coming days," Mr Hynes said, adding there are 5,000 individual faults.
The HSE have warned patients to expect "some disruption" this week as they deal with a backlog of cases. Some elective surgeries have cancelled on Tuesday.
Brendan Lawlor of the HSE asked that people only visit hospital emergency departments and GPS "if it is really necessary".