Wild dogs recently killed four innocent park-goers in Mexico City, and their bodies have been found over the past two weeks. Authorities told the Associated Press that in one case, a teenage girl frantically called her sister with her cellphone to plead for help as the attack took place.

An AP report indicated that the attack took place in Cerro de la Estrella, a partly wooded, hilltop park surrounded by the city's poor and populous Iztapalapa district. The bodies of a 26-year-old woman, and a 1-year-old child were first discovered in the area on Dec. 29, authorities in Mexico's capital said.

According to the prosecutor, as cited by the AP, the woman, Shunashi Mendoza, was missing her left arm with both her and the child having bled to death as well as being partially eaten.

Just days later, a separate group of park-goers discovered the bodies of a teenage couple who had also bled to death.

"Experts have established that due to the gravity of the wounds, at least 10 dogs were involved in each attack," Mexico City prosecutors said in a statement obtained by the AP.

In the second attack, Alejandra Ruiz, 15, and her boyfriend, Samuel Martinez, 16, had gone to the park onFriday afternoon.

That is when Ruiz reportedly called her sister Diana Ruiz at around 7 p.m., pleading for help.

"Several dogs are attacking us, help me!" the girl screamed. The call then stopped.

In an interview with Milenio Television, Ruiz told reporters that she thought her sister was joking. She went on to add that she still doesn’t believe her sister was killed by dogs, despite the call.

"What kind of dog can tear the skin from your whole arm and leave just bone and if it was an attack dog why didn't it attack her neck?" Ruiz asked. "What's most shocking is that one of her breasts was mutilated."

She said she later visited the place of the attack and saw no pools of blood. "There needs to be a thorough investigation," she added.

A spokesman for the Street Dog Protection association in Mexico City  said that the incident does not reflect the behavior of street dogs.

"It's not the behavior of street dogs to kill humans," Antemio Maya, president of the association, said.

Mexico City Public Safety Secretary, Jesus Rodriguez, told Milenio Television that the bodies were not dumped in the area as some had suggested. He said the victims had bite wounds that were inflicted while they were alive and others after they had died.

The AP reported that at least 100 police officers were scouring the park in search of wild dogs, trapping 25 animals by Monday night, including 10 females, eight males and seven puppies. The dogs had been living in caves and crevices in the park, prosecutors said.

Experts said that they are testing the dogs' hair for traces of human blood and will also test their stomach contents. Authorities did not say what they would do with the animals.