I believe it is very rare. It's unfortunate this incident happened, in this particular case, but I think it's very rare that there are people around the airport that late at night. Typically, I believe the department would probably be telling people if it was closing down, and then they would be making arrangements to get to a hotel or make other arrangements. It's an inopportune situation, but at present the airport is closed between 2:00 and 3:30 in the morning.