Schools across Northern Ireland are to close to pupils from Monday due to the coronavirus pandemic, First Minister Arlene Foster has said.
Six new cases of the virus were confirmed in NI on Wednesday, bringing the total number to 68.
Schools in England, Scotland and Wales will close from Friday.
A number of NI schools had already decided to close for the rest of this week. Some are listed on the NI Direct website.
At a press conference on Wednesday, Mrs Foster, standing alongside Deputy First Minister Michelle O'Neill, said now was the right time to shut schools.
"We have agreed that all schools will close to pupils from Monday 23 March," Mrs Foster said.
"The societal and economic impact of this measure will be enormous as parents have to adjust their routine to deal with this unplanned long-term closure."
She added it was a time of "unprecedented challenge" and that the closure would last into the summer.
Stormont sources had earlier incorrectly said schools would close immediately for pupils, and for staff from Monday.
So to clarify Stormont sources incorrect re immediate closure for pupils - closure will kick in from Monday - a number of schools have already covered this week with “development days”— Mark Devenport (@markdevenport) March 18, 2020
Teaching unions had called on Arlene Foster and Michelle O'Neill to set a date for school closures.
Mrs Foster said exploring "how schools can continue to be a base for the education of children whose parents are health service staff or other key workers such as the blue light services" is taking place.
"Educating our children cannot cease and remote learning and home packs for self study are already being explored over the period ahead," she added.
She said clear guidance from the exam bodies is being sought on A-levels and GSCEs, and further details will be made public.
Some clarity, yes, but questions remain
Analysis by Robbie Meredith, BBC News NI education correspondent
A lot of work has to begin now.
For instance, teaching and learning is planned to continue, albeit remotely and a number of schools have put online plans in place, but there could be technological issues with that.
We also know attempts are being made to put in place so-called skeleton schools for the children of healthcare and emergency workers, so could some schools stay open as hub schools for those children?
Efforts are also ongoing to find a way to give free school meals to the 100,000 eligible children.
And we don't know if all childcare facilities are closing. Today's announcement was about schools, and that would include state nursery schools and nursery units, but it's not yet clear if private and voluntary nurseries would also close.
As regards exams, the education secretary in England has said A-Levels and GCSE exams this year, in May and June, will not go ahead.
That seems to indicate there will be no actual physical exams taking place either in Northern Ireland, as the exam regulators across the UK have to act together.
But to be clear, there will still be grades awarded for GCSEs and A-Levels. So there will be no exams but there will be results.
What we don't know is exactly how those results will be awarded yet.
Mrs O'Neill said there was one priority at this time - "to save lives and to mind people".
"We are going to launch a communities response plan, where the voluntary and community sector's emergency leadership group come together to deal with issues such as tackling poverty, food poverty, free school meals, those self-isolating and those people that are connecting with communities," she said.
She also announced a £370m package of measures to help businesses.
"We are going to launch a community support fund, launch an enhanced discretionary support fund, explore support for people in terms of rents," she added.
"We need to look at all these issues and we will communicate all those things to the public in the time ahead."
Teachers' union the INTO said the schools closure announcement "ends the uncertainty for teachers and school leaders, at last".
"This is a worrying time for all concerned but today's decision will go some way to reducing the additional stress levels principals, teachers, parents, children and young people have been enduring over the last week," said INTO northern secretary, Gerry Murphy.
Across the UK, confirmed cases of the virus rose to 2,626 on Wednesday, from 1,950 on Tuesday. A total of 71 people have died.
The UK death toll has now reached 104 after 32 more people died in England after testing positive.
Schools and colleges in the Republic of Ireland have been closed since last Thursday.
Some politicians, including Mrs O'Neill, had been calling for the same action to take place in Northern Ireland.
There are currently 366 confirmed cases in the Republic after 74 new cases were announced on Wednesday.
On Monday all 10 special schools in Belfast announced they were to close indefinitely.
In other developments:
- Libraries NI are to close all public libraries and out of hours access from 17:00 on Friday until further notice
- National Trust opening many of their gardens and park for free but houses, cafes and shops to close
- Presbyterian Church and Methodist Church suspend church services across the island of Ireland
- Apprentice Boys of Derry pull Easter parade and all meetings and services
- The UK death toll has hit 71
- Confirmed cases pass 200,000 worldwide and more than 8,000 people have died