San Francisco ? Since a tiger escaped its pen and killed a person, a snow leopard has ripped a small opening in its wire cage and workers have had to dart a polar bear to goad it into its night enclosure, San Francisco Zoo officials said Friday.

A nearly 100-pound snow leopard managed to rip a 4-inch hole in its wire mesh cage Thursday afternoon and got part of its head and paw out, zoo officials said. The zookeeper could have been harmed if she had not secured the cage, but visitors were never threatened because the cage was in a larger, secured enclosure, zoo spokesman Sam Singer said.

“Even if (the leopard) had escaped, he would have been in another cage so he would never have come in contact with the public,” Singer said.

Last week, employees used darts to goad an obstinate polar bear into its night enclosure so that workers could work to raise the height of the walls there, zoo spokeswoman Lora LaMarca said. The bear never reached a height that would have allowed it to leave, she said.

Singer called the incident a “minor breach” and said the bear was not trying to escape. He denied the wall was raised because of the Jan. 3 incident.

Disclosure of the incidents comes after a 250-pound tiger escaped from its pen and attacked three zoo visitors on Christmas Day. Zoo officials have said the tiger likely climbed over a wall surrounding its enclosure that measured 12 1/2 feet – 4 feet lower than nationally recommended standards – after it was provoked.

Carlos Sousa Jr., 17, was killed in the Dec. 25 attack and his two friends were severely injured.

Zoo director Manuel Mollinedo said the leopard had been moved from the feline conservation area so workers could do maintenance there.

“At no point was there any danger to the public. This was a double containment area,” Mollinedo said