Great Bend ? The 150-pound mountain lion that escaped from a central Kansas zoo enclosure before being killed by police went through a door left open by a zookeeper, zoo officials said.

The 14-year-old female was shot by police at the Great Bend Zoo on Sunday evening. Visitors were still at the zoo, but were quickly evacuated.

Zoo director Mike Cargill said he decided to give law enforcement the OK to shoot after the lion became aggressive as they tried to recapture the animal. Cargill said the cat was “flee or fight,” and already had a reputation for being aggressive.

“Every animal here has a personality,” Cargill said.

The big cat, which was the zoo’s lone mountain lion, was cornered along a fence about 40 feet from the entrance to her own exhibit.

The lion traced the fence to the edge of the zoo’s timber wolf exhibit, became frightened, and ran back toward the grizzly bears. Eventually she crouched in some bushes next to the bobcat exhibit.

Cargill said the cat was never more than 150 feet from her own enclosure.

Great Bend police shot and killed the mountain lion as it crouched near the bobcat exhibit, less than 20 minutes after the escape. Cargill said the cat died instantly.

Cargill said an attempt to lure the lion back to the cages with a path of food failed.

Getting a veterinarian to come to the zoo and prepare tranquilizer darts could have taken 20 or more minutes, which Cargill said was too long. Cargill and the law enforcement personnel didn’t have the medical credentials to use the tranquilizer supply.

There was a concern the lion could leap over the 8-foot-high fence surrounding the zoo, he said.

He was unhappy with the outcome of the situation, Cargill said, but his first concern has to be to control the animal and protect the public’s safety.

“I know a lot of people are upset. I’m upset. I didn’t get in this business to kill cats,” he said.

The disciplinary actions involved in the incident are a part of an internal employee matter and will not be released, the zoo said.

Cargill said there was a past escaped animal at the zoo, a leopard that grabbed a zoo staff member by the head. The staff member survived, but the animal was shot.