DALLAS — "Keke," an elephant at the Dallas Zoo, died just after 4 p.m. Monday after veterinarians worked throughout the day in an attempt to save her.

The Dallas Zoo closed the elephant exhibit Monday to treat Keke, who had colic. Keke had been in critical, but stable condition over the last five days. Zoo officials said the 39-year-old pachyderm ate some rocks, which led to her stomach problems.

Veterinarians were planning to use a crane to lift Keke to her feet for a more thorough evaluation of her situation.

"We began to lift her up," said Craig Hudson, a Dallas Zoo director. "As we got her up, it was obvious she was not going to be able to hold her own weight."

Zoo officials said they had no choice but to euthanize the elephant.

"We care very much about these animals and become very attached to them," Hudson said. "They put in a heroic effort trying to save this animal. It's been a very tough day for us."

Keke lived at the Dallas zoo for nearly five years.

In 2000, the African elephant, who was caught in wild, was loaned to the Caldwell Zoo in Tyler and then moved to Dallas three years later. She came to the zoo as a companion for another female African elephant, "Jenny."

"Everyone who has worked with Keke - not just at this zoo, but at previous zoos - has said if she's not the best they've worked with, she's one of the best," said Chuck Siegel, deputy director of animal management at the Dallas Zoo.

Keke recently made news after the Dallas Zoo's plan to use her waste to generate power.

Keke is the second elephant to die this year in a North Texas zoo. "Babe" died from labor complications at the Fort Worth Zoo in January.