Why did the speaker ask the people to leave the building as quickly as possible?

Ladies and gentlemen, may I have your attention, please. I’m sorry to have to tell you that the police have asked us to take everyone away from this building as quickly as possible. A carrying bag possibly containing an explosive device has been found in one of the dressing rooms at the back stage. Experts are on their way to examine it. We ask you to leave in a quiet and orderly fashion. There is absolutely no need for panic. Please make your way out by exit one. Cross over the road and wait outside the supermarket at the corner of Kings Road. Leave your seats row by row as directed by our attendants and give any assistance necessary to elderly and disabled people. If you have children with you, make sure you are not separated from them. Hold small children firmly by the hand. If you forget anything, please do not try to go back for it. This will cause only unnecessary confusion and delay. If you see any suspicious objects, do not touch them but inform one of our attendants as you leave. Please put out all the cigarettes. We rely on your cooperation and hope you will be able to return to your seats shortly and enjoy the last act of the play.