You're about as likely to be hit by a meteor as eaten by a tiger at the Philadelphia Zoo, a zoo official says.

Reacting to a public case of nerves after a Siberian tiger got out of its exhibit and killed one visitor and seriously injured two others at the San Francisco Zoo on Christmas Day, the Philadelphia Zoo's vice president for animal programs, Andy Baker, said he believes there is no reason to worry about such a thing happening here.

"In terms of people being nervous, you might as well worry about a meteor falling and killing you," he said.

Besides 16-foot vertical fences capped with a 3-foot diagonal overhang leaning in toward the exhibit, the area has "secondary containment," or caging, surrounding that - for the protection of both keepers and visitors, Baker said.

He said he was "confident" that the fencing was "more than a match for the athletic abilities of tigers."

He said jumping an 18-foot fence and swimming a 20-foot moat - as has been speculated as the means of escape for the big cat in San Francisco - is beyond a tiger's athletic abilities. But he wouldn't hazard a guess as to how the animal got loose.

The Philadelphia Zoo has five Siberian tigers. Big Cat Falls, the zoo's exhibit, opened in 2006 and features heavy, triple-paned glass windows and stainless-steel-mesh enclosures.

Baker said the fatal mauling of the visitor to the San Francisco Zoo by an escaped animal was the first such incident in any zoo belonging to the American Zoo and Aquarium Association - although he said disturbed people have been killed after climbing into cages. *