Britain voted to leave the European Union Friday, defying warnings of economic disaster and isolation to deal a thunderous blow to the 60-year-old bloc that sent world markets plunging.
Investors scrambled to sell the pound, oil and stocks as a divided Britain took a lurch into the unknown, becoming the first country to quit in the EU's history, a culmination of decades of suspicion over Europe.
The shock vote also threatened the unity of the United Kingdom, with Scotland unwilling to follow the rest of the country out of the EU.
Voters decided 52 percent to 48 percent in favour of quitting the bloc, a margin of more than one million votes, the final results showed.
"Let June 23 go down in our history as our independence day," said top anti-EU campaigner Nigel Farage, leader of the UK Independence Party, who had promised Britons the chance to retake power from Brussels and rein in high immigration.
"We've done it! We've won!" anti-EU campaigners shouted at the festivities in an office block in Westminster, popping open champagne bottles as "Leave" victories flowed in. "Out! Out! Out!", they chanted as dawn broke.
Sterling collapsed 10 percent to touch a 31-year low of $1.3229. and European stock markets dropped around eight percent at the opening bell.
With markets in tailspin, the Bank of England promised to take "all necessary steps" to secure market stability.
"It's a madhouse in here. It has been a bloodbath. Carnage," said David Papier, head of sales trading at foreign exchange house ETX Capital in London.
Britons appeared to have to shrugged off dire predictions that quitting the 28-nation alliance would create a budget hole requiring spending cuts and tax increases once they lose unfettered trade access to the EU.
Their decision will reawaken fears of a domino-effect ripple of exit votes in EU-sceptic members that could imperil the integrity of the bloc, already struggling with twin economic and refugee crises.
Dutch far-right MP Geert Wilders and French National Front leader Marine Le Pen immediately called for referendums on EU membership in their own countries.
"The eurosceptic genie is out of the bottle and it will now not be put back," Farage said.
Prime Minister David Cameron, who led the ultimately doomed struggle to sway voters in favour of sticking with Brussels, prepared to address the nation.
The foreign minister, Philip Hammond, said Cameron would stay on as British leader. But Farage called for a "Brexit government" to take over.
The bookmakers' favourite to replace the prime minister is former London mayor Boris Johnson, a rival from within his ruling Conservative Party who was the "Leave" camp figurehead.
The result means the world's fifth-largest economy must now go it alone in the global economy, launching lengthy exit negotiations with the bloc and brokering new deals with all the countries it now trades with under the EU's umbrella.
European Commission chief Jean-Claude Juncker has warned the EU will "not be bending over backwards" to help Britain in those negotiations. Analysts say it could take the island nation a decade to secure new trade accords worldwide.
"It looks like a sad day for Europe and the United Kingdom," German Foreign Minister Frank-Walter Steinmeier said on Twitter.
In a worst-case scenario, the International Monetary Fund has warned that the British economy could sink into recession next year and overall economic output would be 5.6 percent lower than otherwise forecast by 2019, with unemployment rising back above six percent.
Thousands of jobs in the City could be transferred to Frankfurt or Paris, top companies have warned. The Brexit camp argued that the business world will adapt quickly, however, with Britain's flexible and dynamic economy buoyed by new economic partners and selective immigration.
Japanese Finance Minister Taro Aso told an emergency press briefing that Tokyo was "extremely worried" about the risks to the global economy and markets but stood ready to respond "firmly".
The campaign has left Britain riven in two, marked by the brutal murder of pro-"Remain" British lawmaker Jo Cox, a mother of two who was stabbed, shot and left bleeding to death on the pavement a week ahead of the vote.
Two years after Scotland voted in a referendum to remain in the United Kingdom, its political leader First Minister Nicola Sturgeon has said a new independence vote is "definitely on the table" after Britain voted against the majority will expressed by Scots.
"Scotland sees its future as part of the EU," Sturgeon told television news after the vote.
Northern Ireland, which is part of the United Kingdom, is now faced with the prospect of customs barriers for trade with EU-member the Republic of Ireland. Irish republicans Sinn Fein called for a vote on Irish unity following the referendum.
Leaders of the European Union, a bloc born out of a determination to forge lasting peace after two world wars, will open a two-day summit on Tuesday to grapple with the British decision.
Immigration and an erosion of economic security have become rallying cries for populist challenges that remain scattered across in Europe, just as they have for Donald Trump's campaign in the US presidential election.