Scottish Deputy First Minister Nicola Sturgeon has said that the thoughts of "everybody across Scotland" are with the bereaved.
She said: "It is impossible to imagine the grief and loss they are experiencing but they should know that the thoughts and prayers of everybody across Scotland are with them at this unimaginably difficult time.
"Our thoughts are also with those who remain in hospital. We all hope and pray that those who have suffered injuries make a full and speedy recovery ...
"The police are not just dealing with a very complex incident, they are also dealing with the loss of colleagues, which makes this situation all the more difficult for them."
More top news
Public Health England has confirmed a strain of bird flu has been detected at a chicken farm in Mid Suffolk on Tuesday.
In parts of China, you can’t just see the smog, you can smell it and taste it.
Mr Johnson urged the British public "to get into the cab of a JCB custard colossus and remove the current blockage we have in Parliament."