21.   Investigators then will spend several days sorting through the pieces in an airport hangar in Aberdeen to find parts that may offer clues to what caused the tragedy.

22.   Lawmakers and other officials are also trying to get inside the collective psyche of such groups so they can prevent them from causing another tragedy.

23.   Officials still have not concluded what caused the tragedy.

24.   Real Ouellette, a Quebec provincial police spokesman, said faulty brakes appeared to have caused the tragedy.

25.   Some believers said the Mothman had come to warn them, while others suggested the entity may have caused the tragedy.

26.   Unocal criticized poor weather forecasts for the gulf, while lawyers representing some of the deceased said inadequate safety standards caused the tragedy.

27.   We cannot allow for racial tensions because it will cause a tragedy.

28.   Investigators earlier ruled out an explosion, bomb or fire on board, saying the tragedy was likely caused by a technical fault or pilot error.

29.   A war would cause tragedy to all Chinese people and should be avoided, the officers added.

30.   Amid uncertainty over what caused the tragedy, the first crash experts flew by helicopter to the snow-swept accident scene on the Arctic Circle island of Spitsbergen.