Tiger that escaped and killed 2

Zoo officials are now saying that a Siberian tiger that escaped her enclosure at the San Francisco Zoo in San Francisco, California on December 25, killing one and severely injuring two humans in the Terrace cafe, may have climbed or jumped over the walls that kept the tiger inside her habitat.

"The animal appears to have climbed or otherwise leaped out of the enclosure. There was no way out through the door," said Robert Jenkins, the zoo's director of animal care and conservation. The tiger has been identified as Tatiana, one of two Siberian tigers at the zoo. The other Siberian, Tony, was not involved in the attacks.

Police, who shot and killed Tatiana, are considering the incident a "crime scene" until they can determine if foul play may have been involved.

"[The incident is being treated as a crime] because we're not certain why the incident occurred - as result of human action or whether this was an incident where the animal was able to get out of the grotto," said Chief of the San Francisco Police Department Heather Fong.

The tigers at the zoo are held captive by the combination of a 20ft (6m) tall wall and a 15ft (4.5m) wide moat. Zoo officials say that there are no cameras around the enclosure, and the incident was not caught on any security cameras.

After the incident, all captive animals were counted and accounted for after the zoo was locked down, including the three other tigers that were in the cage. Earlier reports suggested that all of the tigers had escaped, which later turned out to be false.

Reports say that Carlos Sousa, 17, was killed by Tatiana, but the names of those injured have not yet been released. The human victims were all male, aged from their late teens to mid twenties. Both of the injured, aged 19 and 23, suffered severe upper body and arm lacerations, but their conditions have been upgraded from critical to stable condition at San Francisco General Hospital. It was earlier reported that one of the victims might have been a zoo worker, but later reports state all three were visitors.

"Our two victims, I'm happy to report, are doing very well right now. They are in very stable condition; they're in good spirits," said Dr. Rochelle Dicker to reporters at the hospital during a press conference.

Animal experts don't believe that the tiger attacked for food. Jack Hanna, animal expert and Director Emeritus of the Columbus Zoo in Powell, Ohio states that its possible someone may have "taunted" or "teased Tatiana."

"Were they taunting the animal? I don't know that right now. Were they throwing things that were making it angry? This is a first in this country. I've never heard of an individual (zoo visitor) being killed by an animal. It's much safer going to a zoo than getting in your car and going down the driveway," stated Hanna.

In 2006, another zoo worker was seriously injured by Tatiana while attempting to feed her, but survived the attack.

The zoo's two surviving tigers remain unexhibited while the investigation continues. The zoo currently has two species of tigers, one Siberian and one Sumatran tiger.