NEW : Fireworks , drummers in opening ceremony of 2008 Summer Olympics . Bomb ##ing forces Air China to cancel some flights . President Bush among world leaders in opening ceremony . More than 10,000 athletes to compete for about 200 gold medals .
NEW : Fireworks , drummers in opening ceremony of 2008 Summer Olympics . Bomb threat forces Air China to cancel some flights . President Bush among world leaders attending opening ceremony . More than 10,000 athletes to compete for about 300 gold medals .