Police are carrying out a detailed investigation into what caused a bin lorry to career along a crowded pavement, killing six people.
Five females and one male died while 10 people, including the driver, were injured, Police Scotland have said.
The accident happened in George Square, which was packed with Christmas shoppers and families enjoying the annual winter carnival.
A fleet of private ambulances with police outriders left the crash site early this morning.
A large cordon remains in place and dozens of floral tributes have been placed at the scene.
One witness described the lorry as knocking people down “like pinballs” in the crash which happened at around 2.30pm.
It is thought the driver may have fallen ill at the wheel as he travelled up Queen Street and his vehicle struck a pedestrian outside the Gallery of Modern Art.
The lorry continued on and hit several other people, only coming to a halt when it crashed into the side of Millennium Hotel in George Square.
Chief Inspector Mark Sutherland, from Police Scotland, said: “It’s important that we take all the necessary steps to do it as quickly as we can so that we get the answers for the families and get their loved ones back to them as quick as we can.”
Scotland’s First Minister Nicola Sturgeon said: “My thoughts are with everyone involved in this tragic incident, and especially with the friends and families of the six people who lost their lives in what is another sad day for Glasgow and Scotland.”
Flags on public buildings in George Square will fly at half-mast today in remembrance of those who died and prayers will be said for the victims at a special church service.
The Reverend Alastair Duncan will lead the service at the nearby St George’s Tron at 11.30am.
The tragedy struck just over 12 months after the Clutha Bar helicopter crash in Glasgow.
Ten people died when a police helicopter crashed on to the roof of the pub on November 29 last year.
Church of Scotland Moderator the Right Reverend John Chalmers said: “The news from the city centre of Glasgow just a few days before Christmas is simply devastating.
“For the second year in a row Glaswegians will have to dig deep into their reserves of compassion and sympathy as they support the families of those who have been killed and injured.”
Those injured in the crash, including the driver, continue to receive treatment at Glasgow Royal Infirmary, the Southern General and the Western Infirmary.
Police are appealing to members of the public who have photographs, videos or any type of mobile footage of the incident to send it to a dedicated email address: georgesquareincident@scotland.pnn.police.uk.
Meanwhile, Northumbria Police are investigating an offensive Twitter message relating to the incident.
Speaking on a visit to the scene, Bishop of Glasgow and GallowayGregor Duncan said: “I saw the aftermath in George Square and Queen Street.
“I’ll never forget what I saw but I’m sure that the people of Glasgow are used to tragedy and celebration and they will respond with warmth and care to the people who need their support and solidarity in the days to come. It’s very shocking, very sad.
“Christmas is about light shining in the darkness; the light still shines and we still acknowledge that. In churches all over the city people will be taking time to pray and reflect, to lament and to express their sorrow.”