Updated on Dec. 29 to include a new statement from the adoption agency and details on an upcoming hearing.

A Colleyville couple said their son was mauled by a rescue dog at an adoption event held at Klyde Warren Park in Dallas last Saturday, and they're fighting for the dog to be euthanized.

Allis Cho said she was with her 2-year-old son, Luca Romero, petting dogs at the Dallas Pets Alive adoption event when a pit bull-Labrador mix attacked Luca.

Luca Romero (Courtesy of Allis Cho)

"It was awful," Cho said. "It literally dragged him to the ground and would not let go. It was flailing him around."

Leslie Sans, executive director of Dallas Pets Alive, declined to comment on the specifics of the incident due to a pending investigation but said the rescue agency is reviewing what happened to prevent it from happening again. She said the volunteer-based organization screens all of its animals before bringing them to adoption events and before they are adopted out.

Dallas Pets Alive later released a statement saying the dog, Rusty, most likely bit the child out of fear and that the child was "unattended" at the time of the incident, which Cho disputes.

The agency also said that the dog's true breed is unknown.

Cho said she was told the dogs at the event were friendly and that they were welcome to pet them. She said her son, who loves dogs and is used to playing with their German shepherd, pet several dogs, including the one that later attacked him. It had been friendly toward him at first.

But as Luca was walking back toward the leashed dog, it lunged at him and attacked. Cho said the dog pinned her son to the ground by sinking its teeth into his right arm and chest and wouldn't let go. Bystanders rushed in to help, she said.

"Four to five large men had to come in and literally pry the dog off of him," Cho said. "One of the guys was punching the dog and the dog wouldn't let go of him. It seemed like forever, but I'm sure it was just a minute or two."

Luca Romero shops for a Christmas tree with his family's German shepherd. (Allis Cho)

Her husband, Alan Romero, was at the food trucks nearby when it all happened.

He said authorities were called, and an ambulance took their son to the emergency room at Children's Medical Center Dallas, where he received several stitches on his arm and chest.

The boy's parents said he is doing well but has had some nightmares and is nervous around dogs now.

"What we want is for this dog to be euthanized," Romero said. "It was an unprovoked attack. This dog is dangerous. He mauled a little kid and will probably do it again."

A hearing has been set for next Friday to determine if the dog will be put down, according to WFAA-TV (Channel 8).

Ed Jamison, who recently became director of Dallas Animal Services, said the dog is in the middle of a 10-day quarantine period, during which it will be examined by Deborah Thorne, a DAS veterinarian.

It was Thorne, considered the city shelter's bite specialist, who determined Lamb of God, a yellow Labrador sentenced to death after biting a boy in the face, was a "ticking time bomb" with "multiple personalities."

Jamison said the city will need to determine whether the dog is dangerous, and, if so, whether it can be returned to Dallas Pets Alive. If the city determines that the dog caused serious bodily injury to the child, it could also ask a judge to order its destruction, as it did in the highly debated Lamb of God case. That dog was spared, though, after a judge allowed it to be sent to a no-kill nonprofit in Austin.

"At this point, we don’t know if the dog will go back to the rescue," Jamison said. "They could surrender it or dispute a 'dangerous dog' finding. But we have until the middle of next week to finish the investigation."

Staff reporter Robert Wilonsky contributed to this report.