South Yorkshire will move into the highest tier of coronavirus restrictions from Saturday.
The move, which indicates very high alert, affects about 1.4 million people in the Barnsley, Doncaster, Rotherham and Sheffield local authority areas.
South Yorkshire becomes the fourth region in tier three, following Liverpool, Lancashire and Greater Manchester.
A financial package agreed with the government includes £30m to support the region's businesses and £11m for councils for measures such as test and trace.
Sheffield City Region mayor Dan Jarvis said "inaction was not an option" after the number of people with Covid-19 in the region's hospitals doubled over the last 10 days.
How does England's new three-tier system work?
Every area of England now falls into one of three categories - medium (tier one), high (tier two) or very high (tier three), depending on the local rate of infection.
What are the tier 3 rules?
Areas with the most rapidly rising transmission rates are placed in tier three. The rules will apply for South Yorkshire from 00:01 on 24 October.
You are not allowed to meet socially with anybody who is not part of your household, or support bubble, indoors.
You cannot meet in private or pub gardens, but can meet in parks, beaches, countryside or forests, as long as you are not in a group of more than six.
Pubs and bars must close unless they are serving substantial meals. Alcohol can only be served as part of a meal.
Schools and universities can remain open.
People are being advised not to travel into or out of tier three areas, other than for work, education, youth services or because of caring responsibilities.
Casinos, bingo halls and betting shops, adult gaming centres and soft play areas have closed in all very high alert areas.
Residents should avoid staying overnight in another part of the UK, while those from other regions should avoid staying overnight or holidaying in a tier three area.
You may travel to hotels and other guest accommodation within your own area, but should only do this with people in your household or support bubble.
How are weddings, funerals and places of worship affected in tier 3?
Places of worship remain open, but household mixing is not permitted
What other restrictions will apply in South Yorkshire?
Extra measures can be introduced, following discussions between central and local government.
In South Yorkshire, gyms will remain open with social distancing rules applying for people from different households.
Group exercise classes will remain open, with guidance to restrict numbers and ensure social distancing measures are in place.
What further measures could be implemented?
Through consultations with the Sheffield City Region, the government could bring in additional measures to prevent the spread of Covid-19.
One option would be to close all hospitality apart from takeaway and delivery services.
Leisure centres and gyms could also close, along with public buildings, indoor and outdoor entertainment venues and tourist attractions.
Close contact services such as hairdressers, barbers, beauticians, tattooists and massage therapists could be asked to close.
The closure of performing arts venues for the purposes of performing to audiences could also be brought in.
There is no indication as yet if any of these moves are being considered.
How soon could the measures be relaxed?
In response to a question from Miriam Cates, Conservative MP for Penistone & Stocksbridge, health minister Edward Argar told the House of Commons there would be "open lines of communication" with local leaders in the region.
He said restrictions can be renewed or altered once every 28 days, with a review taking place at least once a fortnight.