"It's a matter of life and death!" the caller screamed, but a 911 dispatcher said there was a delay: Paramedics needed to make sure the tiger loose in the San Francisco Zoo wasn't going to attack them.

Either Paul or Kulbir Dhaliwal made the 911 call from outside a zoo cafe on Dec. 25, asking that a helicopter be brought in to rescue his brother, according to a recording of the call released Tuesday.

By the time the call heard on the nearly seven-minute recording ends, the escaped Siberian tiger already had killed the Dhaliwals' friend, 17-year-old Carlos Sousa Jr., outside the animal's enclosure and was creeping closer to the cafe.

Click here to hear the dramatic 911 call.

"At the cafe, we have the tiger!" an officer shouts into his radio just after 5:27 p.m., according to a recording of police dispatch traffic, about four minutes after the call between the brother and the 911 dispatcher ends. "We have the tiger attacking the victim!"

Less than a minute later, another call comes over the radio to stop shooting.

"We have the cat. We shot the cat," an officer says. "The victim is being attended to."

A separate 911 call placed by a zoo employee who was talking simultaneously with colleagues on a two-way radio revealed that zoo employees initially expressed disbelief that a big cat could have escaped, according to another recording released Tuesday.

The unidentified male zoo employee called 911 at 5:05 p.m. to relay a report from a female employee who encountered the frantic brothers outside the cafe.

"I don't know if they are on drugs or not," the woman is overheard saying on his radio. "They are screaming about an animal that has attacked them and there isn't an animal out. He is talking about a third person, but I don't see a third person."

The man then tries to relay her remarks, when the female employee interjects: "He is saying he got attacked by a lion."

The man is heard on the 911 call, saying, "That is virtually impossible. ... I can't imagine how he could have possibly gotten attacked by a lion. He would have had to have gotten in. I just can't see it."

"I think this guy is on something. He is really agitated," the woman says.

"They don't know if he got attacked by a lion. They are both very agitated and they might be on drugs," the man tells the dispatcher.

At the same time, one of the victims was on another line with a 911 dispatcher, desperately pleading for help and begging to know why it was taking so long to get it, according to a recording of the call.

"I understand that, but at the same time we have to make sure the paramedics don't get chewed out, because if the paramedics get hurt then nobody's going to help you," the dispatcher says.

Seconds later, the brother shouts, "My brother's about to die out here!"

The 911 dispatcher tells him to calm down before the frustrated caller asks, "Can you fly a helicopter out here? Because I don't see a (expletive) ambulance."

Judging by the synopsis of the attacks given by police, the older brother, Kulbir, who was the last of the three victims, likely made the call. The brothers suffered serious bite and claw wounds.

At 5:10 p.m. — five minutes after the first 911 call was made — word reaches the male zoo employee that an animal indeed was loose. He starts telling other visitors that they must leave the grounds immediately.

"We have a Code One. They say they have a tiger out," he tells the dispatcher.

Zoo officials say the tiger had climbed or jumped over the wall surrounding its pen. They have acknowledged that the wall was 4 feet shorter than the recommended minimum height.

The extent of Sousa's injuries became known at 5:15 p.m., when either a paramedic or another zoo employee is heard over the radio reporting a fatality. "This person needs help now," he says.

Michael Cardoza, a personal injury lawyer hired by Sousa's parents, said Tuesday that his clients had not yet listened to the recordings.

Cardoza said he was struck by how cogent the brother who made the 911 call sounded, despite his obvious terror and the initial incredulity of zoo employees.

"That is tantamount to me going up to a cop saying, 'There is a guy with a gun behind our building and he just shot somebody,' and the cop saying, 'Are you on drugs?"' Cardoza said. "Why don't you go check it out first, and then question the reliability of the people who are reporting it, especially when one of them is standing there bleeding?"

But zoo spokesman Sam Singer said the recordings reinforced the zoo director's position that staff "acted heroically in guiding emergency responders to assist the two brothers, as well as to the body of Carlos Sousa Jr."

Also Tuesday, police obtained a search warrant to examine cell phones and car belonging to the Dhaliwal brothers in their criminal investigation, Sgt. Neville Gittens said. The items have been the focus of both police and city officials, who believe they could contain evidence that the victims provoked the tiger in the moments leading to the attack.

Mark Geragos, an attorney representing the brothers, has insisted they did not taunt the animal. He did not return a call for comment late Tuesday.

A hearing on whether the city attorney's office may examine the items in a separate civil case was scheduled for Wednesday.