The San Francisco Police Department is calling the site where a Siberian tiger at the San Francisco Zoo escaped from its cage and attacked three people, killing one, a crime scene.
The 350-pound female tiger killed one man and injured two teenage brothers on Christmas day before the police shot and killed it.
San Francisco Police Chief Heather Fong said that the purpose of a criminal investigation was to determine whether there was any human involvement in the tiger's escape. Fong said that there was no video surveillance, to her knowledge, which could confirm this.
When ABC News' correspondent Miguel Marquez spoke with the public information officer at the San Francisco Police Department earlier today, the officer told him there had been no report of the tiger being taunted by zoo visitors.
A 911 call reporting an injured zoo visitor was placed after closing time at 5:07 p.m. PT, when an estimated 20 visitors were still in the zoo, San Francisco Zoo Director Manuel Mollinedo said during a press conference today.
At the time of the first call, Police Chief Fong said only the Fire Department was dispatched. The police were sent a minute later, she said, when it was determined that the incident might have the potential to become more serious.
Lora Lamarch of the zoo told ABC News that the tiger was enclosed in its regular public exhibit space at the time of the attack, and the one gate leading out of the space was locked. The exhibit is surrounded by a dry moat 25 feet wide and an 18-foot-high wall. If Tatiana did jump out, then she would have had to jump 25 feet across and 20 feet up to escape.
When police arrived, they saw the tiger sitting next to a victim on the ground. According to Fong, the police officers initially held their fire because they were not certain they could contain fire at the animal itself. The tiger was attacking the victim but stopped and looked up when police began shouting at it. When the tiger turned to the officers, the police shot it. It is unclear how many rounds were fired.
Medics rendered first aid to the three victims, one of whom died. The other two were taken to the hospital, where their condition was upgraded from "serious" to "stable" earlier today. They are expected to leave the hospital in the next few days. They suffered from deep bite and claw wounds, which doctors monitored for infection.
The San Francisco Medical Examiner's office told ABC News that the name of the boy killed by the tiger was Carlos Sousa Jr., 17. A source at the San Francisco Police Department told ABC News that the three victims had gone to the zoo together.
Fong said police are collecting firsthand statements from eyewitnesses and looking at physical evidence to determine how the animal escaped.
Last night, police conducted three searches of the zoo until midnight to confirm that there were no other victims on the premises. California Highway Patrol searched using a spotlight and helicopter, and there was also a walk-through of the entire zoo area. This morning, there was another "thorough walk-through" and Fong said she was convinced there are no additional victims.
The same tiger attacked a zookeeper last year, ripping flesh from the keeper's arm, but the animal was not put down because it was not acting in a manner that was atypical of a wild tiger, Mollinedo said. He also said that members of the San Francisco Zoo staff are trained to shoot or put down animals, but the situation happened too quickly for them to act.
Mollinedo said that there were no warning signs, and that the tiger "seemed well adjusted into [its] exhibit" and could usually be found "lying around sunning herself."