Three feral dogs got into the El Paso Zoo overnight, attacking and killing a pronghorn antelope and a sandhill crane.

It was the second attack in five years on the antelope, named Hope by zookeepers, said Nancy Juvrud, the zoo's safety and security coordinator.

"She was traumatized the first time, but not injured," Juvrud said. "She wasn't so lucky this time."

Juvrud said two security guards working Wednesday night heard the attack about 11:45 p.m. As they ran from one end of the zoo to the other, she said, the guards "heard dogs barking and, as they got closer, they heard animal distress noises and snarling."

The dogs, thought to be a pair of pitbulls and a German shepherd mix, were spotted running through the zoo as the guards approached, Juvrud said. The dogs escaped by slipping between a gate and fence, Juvrud said.

Both the antelope and the crane, named Dakota, were dead when zoo officials got to their open, grassland enclosure, which sits about 100 yards from an 8-foot chain-link perimeter fence. No other animals were injured.

Juvrud said zoo officials have not found any holes in the fence that runs along the perimeter.

"There is no hole in the fence. That's the problem, we don't know if they (the dogs) went under it or if there was a loose spot," Juvrud said. "We know they did not come in through a gate and they did not come in over the fence."

Animal control officials in El Paso have not located the dogs.