Labour overturned an SNP majority of almost 10,000 to narrowly win Rutherglen and Hamilton West.
And the Conservatives won Angus from the SNP - where Mike Weir has been defending a majority of 11,230.
But the SNP's Mhairi Black narrowly held Paisley and Renfrewshire despite a big drop in her share of the vote.
Ms Black, the youngest MP at Westminster in the last parliament, had her majority over Labour cut from about 6,000 to about 2,500.
The SNP's Stewart Hosie held Dundee East - which had been the safest seat in Scotland - with Alan Brown also re-elected in Kilmarnock and Loudoun seat, and the party's Martin Docherty holding West Dunbartonshire.
The Conservatives have seen big increases in their in the early Scottish results, with the SNP vote dropping sharply.
An exit poll has predicted that the SNP will lose 22 of the 56 seats it won in the last election.
The poll, which was taken at polling stations across the UK, also suggests the Conservatives will fall short of an overall majority at Westminster.
It predicts the Conservatives will finish with 314 MPs, with Labour on 266, the Lib Dems 14 and the SNP 34.
In Scotland, the Tories had been predicted to win seven seats, the Lib Dems five and Labour two.
A number of seats across the country are said to be too close to call.
Former SNP leader Alex Salmond, the party's current Westminster leader, Angus Robertson among those said to be facing fights to keep their seats.
However, politicians from all parties have reacted to the exit poll with an element of caution, with SNP sources saying they do not believe they will lose as many as 22 seats.
And early results from seats in England showed the Tories outperforming their exit poll prediction.
A full seat-by-seat forecast based on the exit poll is available here.
Political scientist Prof Nicola McEwan told BBC Scotland: "The exit poll and projections are based on probability so it's not just that they've sampled people coming out of the polling stations but they have compared it with the vote shares last time round.
"Some of the seats are more likely to go than others. Within Scotland they're confident - 90%, 80% confident - that the SNP will lose 11 seats.
"The other 11 comes more in terms of the balance of probabilities, perhaps in that 'too close to call' category, including the two Paisley seats, where it's possible Labour might pick up the seats again but they're less confident about it."
The first results in Scotland are due shortly, with the final result of the election expected by lunchtime.
Sources from all parties are, for now, playing down the idea the SNP could lose 22 seats in Scotland, as our exit poll suggests.
But they are trying to work to figure out where the SNP could be vulnerable.
Senior Scottish Tories think early tallies are looking good for them based on their original targets. Scottish Secretary David Mundell thinks his party are within reach of winning all three seats in the south of Scotland.
In Perth and North Perthshire party sources say things are looking good for them. A victory there would be huge for the party - they though they had little chance when the election was called.
Sources in Moray say the race between Tory Douglas Ross and the SNP's deputy leader Angus Robertson is close.
Scottish Labour are playing down the idea they could make significant gains in Scotland, despite suggestions of an increase in the party's vote.
They are confident in Edinburgh South and optimistic in East Lothian. They've also suggested they are doing better in Rutherglen and Hamilton West. But more widely the party things SNP majorities may be too big.
The Lib Dems are positive about Edinburgh West and East Dunbartonshire, two of their three targets in Scotland. North East Fife, where the party thinks it is in with a chance of unseating the SNP's Stephen Gethins, is close, source say.
But with all this, it's early in the night. A long way to go....
Tommy Sheppard, the SNP candidate for Edinburgh East, told BBC Scotland that if the exit poll was "anything like true", it would be a "catastrophic night" for the Conservative party across the UK and could cost the prime minister her job.
On the projections for the SNP's final tally, he said: "Had it not been for the absolutely remarkable result of two years ago, people would have said it was a historic achievement for the SNP.
"Let's try and put it into some sort of perspective. One thing's for sure, the SNP is winning and will win this general election in Scotland and the Conservatives have failed to get a mandate in Scotland."
But Conservative MSP Murdo Fraser told the broadcaster it would be an "astonishing decline" from the unprecedented success the SNP enjoyed two years ago.
Mr Fraser also claimed that a second independence referendum would be "off the table" if the poll proves to be correct.
BBC political editor Laura Kuenssberg said Prime Minister Theresa May took "a high risk strategy" by calling the election.
She added that Mrs May's catchphrase had been "strong and stable leadership", but she may well end the night diminished if the exit poll turns out to be correct.
Scotland's 4,710 polling places opened their doors at 07:00 BST on Thursday, with voting ending at 22:00.
First Minister Nicola Sturgeon said she was "feeling good" as she arrived to vote at Broomhouse Community Hall in the east end of Glasgow amid heavy rain.
The SNP leader gave a thumbs-up to about a dozen waiting photographers before going inside the hall with her husband Peter Murrell.
Scottish Labour leader Kezia Dugdale cast her ballot in Edinburgh, as did Scottish Conservative leader Ruth Davidson.
There were 3,988,420 people registered to vote in the general election in Scotland.
A Scottish Parliament by-election was held in the constituency of Ettrick, Roxburgh and Berwickshire.
Police had stepped up security around the election, with more than twice as many armed officers on duty as on a normal day following the terror attacks in Manchester and London, but there were no reports of any major incidents.
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The SNP has lost two early seats as the first Scottish results are declared in the general election.