Ok I admit, the title is a bit intreaging, so here is the story.
This shot was taken during a festival in the City of Mons in Belgium where a crowd of more than 30,000 people gathered on the main square.
I was shooting the event from a building opposite to that one and was hoping to take a shot with people filling every window.
For quite a long time it didn't happened. People kept coming and going to the windows to watch the show but there were always some empty windows.
Than came the ambulance that you can see in the other photo (emergency call) and was trying to cross through the crowd.
This event brought finally everyone to the windows - and I got my shot.