It has been confirmed that six people have died, but this could rise as casualties are into double figures.
There is speculation that the lorry driver may have taken ill, and possibly suffered a heart attack, at the wheel.
One witness said it was like a “pinball” with the lorry travelling around 150 yards along the pavement, hitting pedestrians as they tried to run out the way.
Roads surrounding George Square are closed as six ambulances dealt with the aftermath.
The Scottish Fire Service tweeted: “Firefighters are in attendance at a serious incident in Queen Street, Glasgow. Our crews are working alongside other emergency responders.”