A similar situation happened on a Swissair flight I was working on as a flight attendant in 1995 or 1996 (can't remember). Also in BRU on a late evening flight back to ZRH. It was on a MD80. During the turn to line up on the runway. A pax suddenly stood and shouted that there was a car and some masked men at the back of the plane. A colleague f/a ran to the cockpit. The first officer opened his window and looked back,...saw what was happening. We then rolled all the way down the runway at relatively high speed and ordered to park in a remote area of the airport. The aft cargo door was open. We then spent some time with pax and police in the terminal. Flight was cancelled and I remember the long, generous drink(s) the whole crew had back at the hotel.