Results from polling stations across the country are rolling in, with an exit poll suggesting the Conservatives will be the largest single party in the new Parliament - but short of an absolute majority.
The BBC/Sky/ITV poll suggested the UK is heading for a hung parliament, with the Tories 12 seats short of the 326 they need for an absolute majority in the House of Commons.
The pound fell more than 1.5% against the US dollar and 1% against the euro as the shock figures set the scene for political turmoil at Westminster, disruption to upcoming Brexit negotiations - and the possibility of yet another election within months.
Here are some of the quotes of election night so far:
- Former chancellor George Osborne, axed under Theresa May, said the exit poll indicated a "catastrophic" night for the Conservatives.
He told ITV: "It is early days, it's a poll, if the poll is anything like accurate this is completely catastrophic for the Conservatives and for Theresa May
"It's difficult to see, if these numbers are right, how they would put together the coalition to remain in office."
- Tory Defence Secretary Sir Michael Fallon told the BBC: "This is a projection, it's not a result.
"These exit polls have been wrong in the past."
- Shadow foreign secretary Emily Thornberry said it was still early but told Sky News: "They have been right for the last 20 years or so, 30 years, so I think we're on the verge of a great result.
"Just think only seven weeks ago the hubris of the Prime Minister who was 20 points ahead, who wanted to have a blank cheque, she wanted to do whatever she wanted with the country with Brexit, with the economy, with our National Health Service and we said no and we meant it."
- Ukip leader Paul Nuttall wrote on Twitter: "If the exit poll is true then Theresa May has put Brexit in jeopardy. I said at the start this election was wrong. Hubris."