Tiger's Deadly Escape Stuns San Francisco

The San Francisco Zoo was closed to visitors and considered a crime scene Wednesday as investigators attempted to determine how a tiger escaped from its enclosure and attacked three visitors, killing one of the men and mauling two others.

The tiger, a female named Tatiana, was the same animal that ripped the flesh off a zookeeper's arm just before Christmas 2006. An investigation of that incident by the California Division of Occupational Safety and Health faulted the zoo, which beefed up the pen where big cats are kept.

The three men - one of them 17-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 zoo grounds near Ocean Beach, police spokesman Steve Mannina said. CBS News has learned the dead teen was Carlos Sousa, of Santa Clara, Calif.

They suffered "pretty aggressive bite marks," Mannina said.

Police searched the zoo grounds during the night, using searchlights and thermal imaging equipment, and again during daylight, and were confident there were no other victims, Chief Heather Fong said at a news conference Wednesday.

Fong said police deemed the area a crime scene "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."

Investigators were gathering physical evidence and taking statements from witnesses, Fong said. She declined to comment on what the surviving victims said about the attack, saying that the investigation was continuing.

Fong added that to her knowledge there was no video footage of the attack.

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

The zoo's director of animal care and conservation, Robert Jenkins, could not explain how the 300-pound tiger escaped. The tiger's enclosure is surrounded by a 15-foot-wide moat and 20-foot-high walls, and the big cat did not leave through an open door, he said.

"There was no way out through the door," Jenkins said. "The animal appears to have climbed or otherwise leaped out of the enclosure."

Jack Hanna, the director emeritus of the Columbus Zoo and a frequent guest on nationally televised talk shows, predicted that other U.S. zoos would reassess their tiger enclosures if it turns out the tiger was able to leap out.

"This is a first in this country," Hanna said in a telephone interview Wednesday. "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."

Hanna said he wasn't familiar with the San Francisco Zoo's tiger exhibit or with Tatiana, but he said that since zoo tigers are well fed, it's unlikely the animal was looking for food.

Hanna said he wanted to know if anyone was teasing the tiger. "Were they taunting the animal? I don't know that right now," he said. "Were they throwing things that were making it angry?"

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, said surgeon Rochelle Dicker. They suffered deep bites and claw cuts on their heads, necks, arms and hands.

Dicker said they were shaken up emotionally and would remain hospitalized for the day, but that because of their youth they would make a full recovery.

The officers who shot the animal were alerted by a 911 call from a zoo employee.

The first attack happened right outside the Siberian's enclosure. The 17-year-old victim, Sousa, died at the scene. A group of four officers came across his body when they entered the dark zoo grounds, Mannina said.

The second victim was about 300 yards away, in front of the Terrace Cafe. The young 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. The officers approached the tiger with their handguns. Tatiana moved in their direction and several of the officers fired, killing the animal.

Neighbors heard the gun shots as police killed the Siberian tiger, reports CBS News correspondent John Blackstone.

Only then did they see the third victim, who had also been mauled.

Although no new visitors were let in after 5 p.m. Tuesday, the grounds had not been not scheduled to close until an hour later, and 20 to 25 people were still in the zoo when the attacks happened, zoo officials said.

The zoo was expected to reopen Thursday, but its executive director, Manuel Mollinedo, said the big cat exhibits will remain closed "until we get a better understanding of what actually happened."

Zoo officials working with experts from other zoos will re-evaluate the big cat facilities "so we can have a better way of managing these animals in the future," Mollinedo said.

There were five tigers at the zoo - three Sumatrans and two Siberians.

On Dec. 22, 2006, Tatiana reached through the bars of her cage and grabbed a keeper, biting and mauling one of the woman's arms and causing deep lacerations. The zoo's Lion House was temporarily closed during an investigation. California's Division of Occupational Safety and Health blamed the zoo for the assault and imposed a $18,000 penalty.

After that attack, the zoo added customized steel mesh over the bars, built in a feeding chute and increased the distance between the public and the cats.

Mollinedo said zoo officials did not consider putting Tatiana down after the earlier attack, because in that case "the tiger was acting as a normal tiger does."

Tatiana arrived at the San Francisco Zoo from the Denver Zoo a few years ago, with zoo officials hoping she would mate with a male tiger. Siberian tigers are classified as endangered and there are more than 600 of the animals living in captivity worldwide.