Two pensioners have been critically injured by a bus in central Glasgow.
The elderly couple, who have not been named, were struck by a double-decker First Glasgow service, at the corner of Argyle and Queen Street, at 14:30.
Eyewitnesses described "horrific" and "hysterical" scenes in the aftermath of the accident.
Eyewitness Jan Watson said: "We were coming out from Primark and we saw the bus coming along and going round the corner. It just stopped dead. We approached the crossing and people were coming round and we just followed the people. We saw a woman trapped underneath the wheel."
"There was a lot of shouting and screaming. A few people were hysterical because they had actually witnessed it. It was horrific," she added. "I saw part of the lady and saw something under the wheel which I have been told is an elderly man."
Jordan Macrae, 18, told BBC Scotland he was coming out of a shop on Argyle Street when the crash happened.
"From what we could see there was two people under the bus," he said. "It was horrible. There was screaming. Everyone was on their phone trying to call the emergency services. Everyone was crowding round, trying to see if they could help. The people that went and helped were really good."
The pensioners were released from under the bus using airbags and taken to the city's Royal Infirmary.
The bus driver was uninjured but said to be extremely shaken as a result of the incident.
Sgt Andrew Mair from Police Scotland said: "Where the crash happened is an extremely busy shopping area, and I would appeal to any witnesses who have not yet spoken to police to contact us."
25 fire-fighters from the Scottish Fire and Rescue Service were on the scene. A spokesman said: "Scottish Fire and Rescue Service crews attended an incident in Queen Street in Glasgow city centre following a call from ambulance control around 2.35pm.
"Four appliances from Calton and Cowcaddens community fire stations attended the incident along with a heavy rescue vehicle from Easterhouse. The fire-fighters, who were working closely with paramedics and doctors, used airbags to release two people from beneath a bus. Both casualties were taken to Glasgow Royal Infirmary by ambulance."
A spokeswoman for First Group said: "We can confirm an incident occurred this afternoon involving a First Glasgow service and two pedestrians. We are doing everything we can to support the emergency services and a full investigation to establish exactly what happened is under way."
A police investigation into the incident is under way.