Nicola Sturgeon paid tribute to Glasgow's emergency services after a bin lorry crashed into a crowd of pedestrians in the centre of the city.
The First Minister of Scotland, speaking at the scene of the crash at George Square, also shared her condolences to the families of the six people killed in the incident.
The leader of the Scottish National Party (SNP) said Glasgow had become "broken-hearted" following the "awful tragedy".
"I would like to take this opportunity again to convey my deep condolence to the bereaved families, those who have lost loved ones in this awful tragedy," Sturgeon said.
"My thoughts are also with those who remain in hospital, having sustained injuries, and with the many members of public who witnessed traumatic scenes that I'm sure that will live with them for a very, very long time.
She added: "I also want to take the opportunity to thank from the bottom of my heart our emergency services – our police, our fire service, our ambulance workers. They do an excellent and professional job.
"We were reminded of how often they are called upon to go beyond to call of duty and all of us are deeply grateful for the job they do on our behalf, seeking to keep us safe.
"Glasgow, this morning, is a broken-hearted city. 2014 has been such an incredible year for this wonderful city.
"The Commonwealth Games were such an outstanding success. But it's a year that's been book-ended by two unimaginable tragedies, The Clutha at the end of last year and now this awful tragedy."
Authorities said eight people remain in hospital receiving treatment for injuries sustained in the crash.
Two grandparents and their granddaughter were among those killed.
Jack and Lorraine Sweeney, aged 68 and 69, and 16-year-old Erin McQuade were named on social media by relatives on Tuesday (23 December).
A memorial service has been held for the six people who were killed after the lorry lost control and careered into a hotel after climbing the pavement.
The service took place at St George's Tron, close to the scene of Monday's tragedy in George Square.
Candles were lit and a minute's silence was observed, at the ceremony led by Rev Alastair Duncan, who said "each death was a personal tragedy".