British Prime Minister Boris Johnson has tested positive for the coronavirus and is exhibiting "mild symptoms". His Health Secretary Matt Hancock later announced he, too, was positive.
In a video posted on his Twitter feed, Johnson said he had experienced "a temperature and persistent cough" over the last 24 hours and, on the advice of the chief medical officer, took a test which confirmed he had contracted Covid-19.
According to Downing Street, the Prime Minister is continuing to lead the Government's coronavirus response.
It comes as overall death toll in the UK has risen to 759 - another 181 people have died in the last 24 hours, the biggest daily rise. More than 14,500 people have now been infected.
That figure includes the Health Secretary as well as Johnson. Hancock also announced on Twitter today that he has tested positive for Covid-19.
And in a further development, England's chief medical officer, Professor Chris Whitty, said he was experiencing symptoms and would be self-isolating at home for the next seven days.
The bombshell news threatens to send the government's response into chaos, with speculation rampant over who else might be infected at the highest echelons of the state.
The politicians are believed to have carried out a slew of face-to-face meetings over the past week. But Downing Street insists there is no need for other ministers or officials to get checked unless they start displaying symptoms.
The drama kicked off overnight (NZT) when Johnson declared he had coronavirus. Chief Medical Officer Chris Whitty advised him to get a test after he developed a temperature and cough yesterday afternoon.
The 55-year-old insisted he only has "mild symptoms", and will be continuing to lead the national response over video-conference. The PM will stay in his flat in No11 - from where he chaired a meeting of the "war Cabinet" this morning - and aides will leave meals and work outside the door.
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Within hours Hancock then revealed he also has the virus. "I've tested positive. Thankfully my symptoms are mild and I'm working from home & self-isolating," he tweeted.
Hancock had been expected to appear at the daily government press briefing, but Michael Gove is now likely to fill in.
Despite the government's own guidance saying people must self-isolate for 14 days if anyone in their "household" develops symptoms, no senior figures - such as Chancellor Rishi Sunak who was with the PM last night or chief aide Dominic Cummings - are thought to be going into isolation.
Cummings was seen making a hasty exit from Downing Street today carrying a rucksack.
Johnson's pregnant partner Carrie Symonds is believed to be in self-isolation, although it is not known when they last saw each other or if she has been checked.
In a video, Johnson said: "Hi folks I want to bring you up to speed on something that is happening today which is that I have developed mild symptoms of coronavirus, that is to say a temperature and a persistent cough, and on the advice of the chief medical officer I have taken a test.
"That has come out positive so I am working from home, I am self-isolating.
"That is entirely the right thing to do but be in no doubt that I can continue thanks to the wizardry of modern technology to communicate with all my top team to lead the national fight back against coronavirus."
Downing Street has previously said that Foreign Secretary Dominic Raab will fill in if the PM is incapacitated, although there is little sign that he has stopped working.
Politicians and experts have been quick to react to the news that Johnson has contracted the coronavirus.
Labour leader Jeremy Corbyn said on Twitter that he wishes the Prime Minister "a speedy recovery and hope his family are safe and healthy".
"Coronavirus can and does affect anyone," Corbyn added.
The Labour leadership contender, Sir Keir Starmer, also wished Johnson a "speedy recovery", adding that "together we can and will come through this".