The United Kingdom will no longer remain in the European Union, voting 51.9 percent to 48.1 percent in favor of the "Brexit" referendum.
Prime Minister David Cameron announced, shortly after the decision became clear, that he will not remain in office and will step down by October.
"I do not think it would be right for me to be the captain that steers our country to its next destination," he told reporters outside his Downing Street office in London, NBC News reports.
The decision by voters also sent the global markets reeling, with the British pound plunging to a value of $1.35, the lowest it has been since 1985, according to NBC News.
The vote, the BBC notes, has also brought up internal issues within the United Kingdom as voters in London, as well as in Scotland and Northern Ireland, all backed remaining in the European Union.
According to the BBC, Scottish First Minister Nicola Sturgeon said she was "absolutely determined" to keep Scotland in the European Union, and so it was "highly likely" that a second referendum for Scottish independence would be forthcoming.
Sturgeon, the BBC notes in another report, said it was "democratically unacceptable" that Scotland faced being taken out of the EU against its will, with Scottish voters casting ballots in favor of the U.K. remaining in the EU by 62 percent to 38 percent.
Meanwhile, the remaining members of the European Union are attempting to grapple with the loss of the U.K. According to a separate report by the BBC, the European Parliament called a special session for Tuesday to assess the vote. Ministers of the six founding nations of the European Union—Germany, France, the Netherlands, Italy, Belgium and Luxembourg—are scheduled to meet in Berlin on Saturday.
Heads of the EU's main institutions released a statement asking the U.K. to sever its connections quickly and efficiently "as soon as possible, however painful that process may be. Any delay would unnecessarily prolong uncertainty."
The statement was signed by European Council President Donald Tusk, European Commission President Jean-Claude Juncker, European Parliament President Martin Schulz and Dutch Prime Minister Mark Rutte, holder of the rotating presidency of the Council of the EU.
"In a free and democratic process, the British people have expressed their wish to leave the European Union. We regret this decision but respect it," the statement read. "This is an unprecedented situation, but we are united in our response. We will stand strong and uphold the EU's core values of promoting peace and the well-being of its peoples. The union of 27 member states will continue."
The results of the referendum are also raising questions about the United Kingdom's relationship with the U.S., NBC notes. President Barack Obama had encouraged voters to swing in favor of remaining in the European Union.
According to NBC, a White House official said Friday that Obama had been briefed on the referendum and will speak to Cameron over the course of the day.
Presumptive Republican presidential nominee Donald Trump said Friday that he sees the referendum vote as a "great thing."
"I think that it's a great thing," he told reporters while visiting Scotland. "They took back their country.”