Extreme weather and jack-knifed lorries combined to cause "significant challenges" on one of Scotland's main roads where motorists were stranded overnight, the Deputy First Minister said.
John Swinney said there had been an "extensive operation" taking place to try to get traffic on the M80 motorway - which links Glasgow and Stirling - moving again.
Motorists reported being stuck for up to 13 hours, with some spending the night in their cars, and others abandoning their vehicles on the motorway.
Emergency responders and volunteer agencies, including mountain rescue teams, checked on stranded drivers, with some good samaritans also handing out food.
Been stuck on this bus on the motorway for 3.5 hours in the snow chaos. A guy who lives nearby just came on handing out water and snacks donated by his local shop. What a guy! That's the scotland way! ?? #snow#M80pic.twitter.com/XTGy4tY57f
-- Rachel Muircroft (@rachmuircroft) February 28, 2018
HGV driver Alex Downie from Dundee said he had been stuck on the M80 near Castlecary since 5pm on Wednesday.
He told BBC Radio Scotland: "The northbound M80 is moving but southbound we have been stationary, I haven't moved since 5.10 last night.
"A few volunteer people came up and down the roads, it must have been about one o'clock this morning, a gentleman came over from his house with provisions and passed them out to people in cars.
"The police came round on the northbound carriageway at four this morning and informed us that the road was open and we would be moving again. That was the last police car we seen, that was the last information we had as well."
It happened after the first ever red weather warning was issued for much of central Scotland, with people advised not to travel.
Mr Swinney told BBC Radio Scotland the country was experiencing "the most significant snow incident we've had since 2010".
And he said the M80 had been a "particular pinch point" after traffic ground to a halt.
-- Tricia Lee (@TriciaLee99) February 28, 2018
Speaking on the Good Morning Scotland programme, the Deputy First Minister said: "The M80 has presented much more significant challenges to us overnight and there has been a very strong operation to try to gain traction over the course of the night.
"Although many people were stuck for a long time we did get the road moving quite significantly, but there are people who have been stuck there for a long time.
"That's a combination of the intensity of the snow, but also the fact that we have had quite a number of jack-knifed lorries on that particular stretch of the road and the minute that happens the road gets blocked and nobody can get through."
He said the "overwhelming majority" of Scots had heeded warnings to stay at home.
"Many people have responded to those warnings very significantly but we do face challenges at particular pinch points, and the M80 has been our most difficult situation to try to manage," he said.
"I assure members of the public there has been an extensive operation in place to try to maintain traction on that road and to get motorists on the move as quickly as possible."
He also stressed people should stay at home today unless they are essential workers.
Mr Swinney stated: "People should avoid travel for the whole of today, that's the clearest and the sharpest warning I can give, that people should avoid travel today to give us an opportunity to clear the incidents we have and to give us an opportunity to recover the network for the safe movement of individuals in due course
"My encouragement to people for the whole of today is not to travel unless they are an emergency worker, because if they do that that will help us maintain public services, get essential workers to where we need them and to make sure that people are safe."