Several pedestrians are feared dead after a bin lorry crashed into a group of people in George Square in Glasgow city centre.
Police have not confirmed reports of up to six fatalities but described the crash, outside Queen Street station at about 14:30, as "very serious".
Eyewitnesses reported the bin lorry moving at speed up Queen Street before hearing a bang as it hit a hotel.
Several people were seen lying on the ground following the crash.
Restaurant owner George Smith told BBC Scotland: "It [the lorry] started from the bottom of Royal Exchange Square and crashed into the wall at the Millennium Hotel.
"A customer walked into our restaurant and told us what happened outside. We walked outside and in the first five minutes the first ambulance arrived.
"The police and ambulance arrived quite fast. I was quite surprised because they were very, very fast."
Describing the scene on Twitter, Brett Molloy tweeted: "Whole of George square is shut off, bodies on the road. Scary man.
"Horrible, horrible scenes. Even worse at this time of the year.
"City centre is an eerie, eerie place right now."
'Really sad'
Kevin @km747 tweeted: "Horrific scenes in George Square. Here now and it's clear to say lives have been lost."
Restaurant owner George Smith told the BBC he had heard that the bin lorry driver had suffered a heart attack and the vehicle had careered along the street before hitting the pedestrians outside the Millennium Hotel.
He said that the emergency services were on the scene within minutes, adding: "It's really, really sad."
A large number of emergency vehicles are in attendance and roads surrounding George Square have been closed.