We expect to hear these news from the villages of India. But this crime scene occurred Wednesday at the San Francisco Zoo: an escaped Siberian tigress killed one visitor and mauled two others. The 300-pound (136-kilogram) Tatiana had been already involved in an attack on a zookeeper last Christmas. That incident made the Zoo improve the pen where tigers were kept.

"The three men-one of them 19 years old and the others in their early 20s-were attacked just after 5 p.m. Tuesday on the east end of the 125-acre (50-hectare) zoo grounds near Ocean Beach", police spokesperson Steve Mannina said.

"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 Heather Fong.

"The San Francisco medical examiner had not been able to identify the dead man. The man did not have any identification and no one had called asking about him", said investigator Tim Hellman.

How the escape occurred is a mystery.

"The tiger's enclosure is surrounded by a 15-foot-wide (4.5-meter-wide) moat and 20-foot-high (6-meter-high) walls, and the big cat did not leave through an open door. There was no way out through the door. The animal appears to have climbed or otherwise leaped out of the enclosure", said zoo's director of animal care and conservation, Robert Jenkins.

"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", Jack Hanna, director emeritus of the Columbus, Ohio, zoo told National Geographic News.

"Since zoo tigers are well fed, it's unlikely the animal was looking for food."

He believes the animal could have been stressed by people.

"Were they taunting the animal? Were they throwing things that were making it angry?"

The other two victims are recovering.

"The two injured men, ages 19 and 23, were upgraded to stable condition Wednesday at San Francisco General Hospital after surgery to clean and close their wounds. They suffered deep bites and claw cuts on their heads, necks, arms and hands. They were shaken up emotionally and would remain hospitalized for the day, but that because of their youth they would make a full recovery", said surgeon Rochelle Dicker.

The first attack and kill occurred right outside Tatiana's enclosure. The second victim was made at about 300 yards (275 m) away, in front of the Terrace Cafe.

"The man was sitting on the ground, blood running from gashes in his head and Tatiana sitting next to him. The cat attacked the man again", Mannina said.

Tatiana then attacked the police officers and they fired, killing her.

San Francisco Zoo was keeping five tigers: three Sumatrans and two Siberians.

On December 22nd, 2006, the same tigress grabbed through the bars of her cage a keeper, biting and mauling one of her arms. The Zoo was imposed then with $ 18,000 penalty. Since then, the zoo increased the distance between the public and the cats.

Tatiana had been brought some years earlier from the Denver Zoo for a breeding program. Siberian tigers are extremely menaced: about 200 are found in the wild, and the hope is found in zoos, where 600 individuals are found worldwide. Even if Siberian tigers are the largest tigers (and cats) ever, the Indian (Bengali) and Sumatran (the smallest type) tigers are more famous for their bad temper and taste for human flesh.