Behind them: a bloody tiger enclosure and one dead man, fatally mauled.

Ahead of them: the Terrace Cafe and the sight of a 243-pound Siberian tiger sitting in front of her next victim, toying with the man as a cat would play with a wounded mouse.

Across the way, Officers Kevin O'Leary and Daniel Kroos had just arrived in their radio car. The man with the tiger was screaming, begging for help.

Armed only with their .40-caliber handguns, the officers had to figure things out in a heartbeat. Shoot. Don't shoot. Distract the tiger. Wait for help.

"I never could have imagined having to deal with something like this," Biggs said. "We never got any instruction on dealing with wild animals when we were at the academy."

Moments later, Tatiana left her victim and turned her attention on the four officers, leaving them with one choice. They responded with a deadly hail of gunfire, and the Siberian tiger soon was dead.

For their actions, Oshita, 31, Biggs, 37, O'Leary, 40, and Kroos, 29, will receive the San Francisco Police Department's highest award for bravery - the gold medal of valor - at a ceremony tonight at City Hall.

The officers have said nothing in public until now because of investigations into the incident as well as pending lawsuits. But, as the department prepares to honor the men, three of the four agreed to tell the story of what happened that night at the zoo.

Just before dusk that day, 17-year-old Carlos Souza Jr. and two brothers, Paul Dhaliwal, 19, and Kulbir Dhaliwal, 23, were at the tiger enclosure when Tatiana turned, leaped over the retaining wall and went on the attack. Zoo officials have said the men must have taunted or somehow bothered the tiger. An investigation has never conclusively proven that.

The tiger killed Souza immediately, then chased Paul Dhaliwal about 300 yards to the zoo's Terrace Cafe and was in the process of attacking him when the officers arrived.

Plainclothes partners Oshita and Biggs were in one car, and uniformed officers O'Leary and Kroos were in another. The first calls came in just after 5 p.m. The initial radio broadcast indicated that a zoo patron had been bitten by "an exotic animal."

"I thought it must have been some other animal, something small, like just a small bite that needed to be handled," Oshita said.

In any case, they responded to the zoo as quickly as possible and learned immediately that a tiger was on the loose.

O'Leary and Kroos (who declined to be interviewed for this story) went to the zoo entrance and used their loudspeaker to order patrons out of the zoo.

A gruesome discovery

Oshita and Biggs went to the tiger enclosure, where they found Souza. It was not a pretty sight, the officers recalled. Gruesome, in fact, they said.

The officers' faces went white at the memory of the scene.

Dusk had settled by now, and they knew a man-killing tiger was on the loose, with plenty of places to hide.

A zoo employee called to them. The tiger, he told them, had gone to the area by the Terrace Cafe, where it had attacked another person.

The officers, with the employee in the backseat, drove slowly down a service road toward the cafe. They looked left and right, up and down, for signs of the tiger.

They were not thinking about confronting or killing the tiger, they said. Their mission was to find and help victims and to secure the area.

That all changed when they came upon the scene at the Terrace Cafe.

At about the same time, O'Leary and Kroos reached the cafe from a different direction. All four officers saw the same thing: Dhaliwal was sitting on the ground, legs extended in front of him, bleeding from the head and screaming for help. Tatiana was sitting in front of him, looking at him.

The officers - 35 yards away - yelled, whistled and tried to get the tiger's attention. They wanted the animal to move away from her victim.

The noise startled the tiger; she reared up on her back legs and started swatting at Dhaliwal, toying with him.

Tiger coming on fast

The officers could not shoot for fear of hitting the young man. They made more noise.

Finally, the big cat turned and looked at Oshita, who was standing with his partner in front of their car.

"She looked angry," Oshita said.

The tiger started toward the officers. By now, O'Leary and Kroos had made their way to the left of Oshita and Biggs.

Oshita said the tiger moved quickly - not running; more of a lope. Whatever, it was fast.

Oshita, who had his .40-caliber semiautomatic pistol drawn, fired three rounds. Two shots hit the tiger in the chest. Oshita said he could see the tiger's hair part, as if someone had blown on it.

"The bullets didn't even slow her down," Oshita said. "She just had this look on her face like, 'Are you kidding me?' "

And Tatiana kept coming.

The officers retreated to their car. To their horror, they saw that the passenger side window was open and they had no time to roll it up. The tiger had a place to attack.

O'Leary and Kroos started firing from their positions to the left. Oshita, in the passenger seat with the open window, leaned out of the car and fired twice more at the oncoming tiger.

Biggs, making a split-second decision, jumped out, ran around to the front of the vehicle where bullets had finally caused Tatiana to stumble to the ground. Worried that the big cat would leap up for one last attack, Biggs shot her once more.

Tatiana, the biggest, baddest, most majestic cat in the house, turned and lay her head down. She was dead. The time was 5:27 p.m.

It was later determined that Tatiana had been hit seven times: twice in the head and five times in the chest.

The officers said they have no lingering emotional issues related to their action.

O'Leary, who saw combat as a soldier during the first Gulf War, said war was worse than the tiger attack. But he conceded that what happened that night at the zoo was surreal and difficult to digest because the fight was different. In war, it's soldier vs. soldier. But you never know what a tiger will do or even how to kill the beast, he said.

"No one wanted to shoot that tiger," Biggs said. "She was a beautiful animal. It was just an unfortunate situation. We didn't have any choice."

E-mail John Koopman at jkoopman@sfchronicle.com.

This article appeared on page A - 1 of the San Francisco Chronicle