Czech Airlines flight OK481 was about to depart on Friday afternoon, 3 August 2018, as a scheduled flight from Helsinki to Prague.
The aircraft was an Airbus A319-112 registered OK-PET.
There were 135 passengers and five crewmembers on board.
Czech Airlines flight OK481 was taxiing along taxiway D towards runway 22R. 

During taxiing passengers and the cabin attendants detected grey smoke in mid-cabin.

The smoke got thicker and one of the attendants sitting in the aft cabin used the interphone and reported this to the purser, who was positioned in the forward cabin. The purser reported this to the captain by interphone, who then stopped the aircraft on the taxiway.
Some passengers stood up and shouted to the cabin crew that there was smoke inside the aircraft.
Evacuation was initiated by the crew.

Emergency slides were used during the evacuation. During the evacuation some passengers rushed past slower-moving passengers.
Among others, children were trampled over.
Furthermore, passengers stumbled over carry- on luggage in the aisle.
During the evacuation 26 passengers sustained minor injuries.
The purser considered the situation to be life-threatening and notified the captain of the need to evacuate immediately.
The captain was faced with an unforeseen situation.
He notified the ATC of smoke inside the cargo compartment, even though there were no indications of smoke there.