Labour shadow foreign secretary and campaign co-ordinator Douglas Alexander and Scottish Labour leader Jim Murphy have both lost their seats to the SNP.
As David Cameron is on track to return to Downing Street as prime minister, perhaps even with an overall majority, Nicola Sturgeon's SNP looks set to rampage across Labour's Scottish heartland - taking 58 of Scotland's 59 seats.
Scottish voters are handing the Scottish nationalists huge swings against Labour. Alexander had had a majority of more than 16,000 going into the election, but Mhairi Black - who is likely to be the youngest MP - easily overturned that. She polled 23,548 votes, ahead of Alexander, who had 17,864.
Newly elected Scottish National Party (SNP) member of parliament, Mhairi Black (R), Britain's youngest member of parliament since 1667, greets Labour candidate Douglas Alexander.
Former SNP leader Alex Salmond set the tone for the fight between the SNP and the Conservatives, suggesting a Tory government that had no Scottish MPs would not be legitimate.
"There's going to be a lion roaring tonight, a Scottish lion, and it's going to roar with a voice that no government of whatever political complexion is going to be able to ignore," he said.
Ed Miliband's leadership of Labour was already being questioned in the early hours of Friday morning, as the exit poll predicted he would secure just 239 seats - 17 fewer than their tally at the start of the election campaign.
It looks like an awful night for Nick Clegg and the Liberal Democrats who may see their party reduced to a rump of just 10 MPs - down from the 57 the party had in the last parliament.
Ukip, according to the exit poll, could win only two MPs despite possibly ending up as the third largest party in terms of national vote share. Nigel Farage is also rumoured to have failed to win the fight for South Thanet, which would likely see him quit as party leader.
Professor John Curtice, the BBC's election guru, pointed to the result in the marginal Nuneaton seat as a hint Cameron may be able to win a majority. "We were expecting a one-point swing to Labour in Nuneaton. In practise with a three-point swing to themselves, the Tories have succeeded in defending this highly marginal seat. In practise we now have to take seriously the possibility that the Tories could get an overall majority," he said.
