Moody Gardens staff members arriving to work early Monday morning discovered two sharks dead and two others barely moving at the bottom of the exhibit, unusual behavior for the fast-moving, aggressive hunters, said Jerri Hamachek, marketing and public relations manager.

Divers tried for almost an hour to revive the two blacktip sharks by injecting them with steroids, but it was too late, Hamachek said. "It all happened so quickly," she said.

Other exhibit animals, including sand tiger sharks, brown sharks, sea turtles, eels and tropical fish, were not affected. Hamachek said the sharks, first introduced to the exhibit two years ago, were especially sensitive to ozone changes.

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