Suspected poison hidden inside sausage at Parque España in Mexico City might have killed at least three dogs Tuesday, prompting a criminal investigation and warnings for pet owners in the capital’s Condesa neighborhood.

The Mexico City Attorney General’s Office opened an animal cruelty investigation after dogs became ill following walks in the 105-year-old park.

Residents reported four deaths, according to Uno TV, while Cuauhtémoc borough Mayor Alessandra Rojo de la Vega reported at least three, Infobae reported.

Police found a piece of longaniza, a seasoned sausage, containing a blue pill with white powder inside, La Crónica reported. However, authorities had not publicly identified the substance or established whether it was linked to the dogs’ illnesses.

Residents also reported finding suspected poisoned meat one block from Parque España, at the intersection of Avenida Veracruz and Calle Atlixco, La Crónica reported.

Excélsior reported that five dogs arrived at the Vetme veterinary hospital suffering from seizures, prompting staff to alert authorities. Three died and two remained hospitalized.

Among those that died was Rufián, a 4-year-old Irish setter-golden retriever mix.

“Three minutes after he arrived home, he started convulsing,” said Sofía Suárez, the dog’s owner and the mother of a 2-year-old.

“How am I going to tell my daughter that she doesn’t have a dog anymore? We’d go to the park every morning and every afternoon,” she said.

Two other dogs, a Belgian shepherd named Kiara and a small-breed dog named Siberia, remained hospitalized, Excélsior reported. 

Their owner, Brenda Gómez Magaña, told the newspaper that blue capsules were recovered during a stomach lavage. Kiara appeared to be improving, while Siberia remained in serious condition.

Rojo de la Vega requested a review of surveillance footage and announced legal assistance for families filing complaints.

Investigators were collecting owners’ statements, examining evidence and seeking help from veterinary specialists. Excélsior reported Tuesday evening that authorities had collected nine pieces of evidence suspected of containing poison.

A neighborhood representative said the park would remain open, but its popular dog run and children’s areas would close pending cleanup. Residents wanted the entire park cleaned once prosecutors authorized the work.

Authorities began preventive patrols. Rojo de la Vega urged visitors to Parque España and nearby Parque México to prevent pets from eating anything off the ground and report information to investigators.

With reports from Infobae, Uno TV, Excélsior and La Crónica