Police thought 911 calls reporting a deadly tiger attack was a prank

San Francisco police initially believed that desperate 911 calls reporting a deadly tiger attack at the city's zoo was a prank.

Police records show that officers struggled to reach the victims of the attack as zookeepers had locked down the zoo.

One man was killed and two badly injured when 350lb Siberian tiger Tatiana leapt out of her compound and launched her lethal attack.

The records show that after the tiger was shot and killed the drama continued for 23-minutes with park staff believing four more were on the loose.

Police were dispatched when one of the bitten men screamed to a park worker that the tiger had bitten him.

But the police remained initially skeptical. "Zoo personnel dispatch now say there are two males, who the zoo thinks are 800 (mentally unstable) and making something up," a police dispatch recorded.

"But one is in fact bleeding from the back of the head."

Carlos Sousa Jr., 17, was killed by the tiger, outside the animal's grotto.

Paul and Kulbir Dhaliwal, both 23, required hospital treatment but have now been sent home