(CNN) A zoo killed two lions to save a man who jumped into the big cats' enclosure in the Chilean capital.

The man climbed over the fence Saturday and removed his clothes before approaching the lions, according to a statement posted on the Santiago Metropolitan Zoo Facebook page.

He was apparently attempting suicide, and a note was found in his clothes, Chilean media reported

Zoo staff shot and killed two of the lions with live rounds to protect the man, the zoo's statement said.

"Due to the circumstances and to firstly protect the life of this person, we found ourselves obliged to apply all of our security protocols," the zoo's statement reads.

The two lions, a male and a female, were shot in front of a large crowd of zoo visitors. The male lion was born at the zoo, while the lioness was rescued from a circus, local media reported.

The zoo said it took the "incomprehensible action" of killing two of its three lions, which was "profoundly painful for every single one of us."

The man has been described by police as "frustrated" and an investigation has been opened.

'Very apocalyptic, very religious'

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Once he had entered the enclosure, the intruder removed his clothes he began to bother the lions, to jump towards them and to chant "very apocalyptic, very religious" proverbs, the park's director, Mauricio Fabry told CNN. He was mauled by the lions, which began dragging him to their den, before they were shot. The man was hospitalized in serious condition.

"It was imminent (to) save this man and we had to shoot the lions," Fabry said.

"We took the unconscious young man to the ICU at the Indisa Clinic where he remains today in grave condition," he added.

The decision to shoot the cats was made because tranquilizers do not take effect for several minutes and the man's life was in danger as the lions were already attacking him.

"The young man had a letter. I don't know if it would be categorized as a suicide note. It was very Christian and it had drawings of lions. He was the lions in the drawings, with things that said, 'I am the lion,'" Fabry said, adding that the man's mother had recently died.

Another local report stated that the victim had signed the note "Jesus" and said that God would protect him.

The zoo remained open over the weekend, with only the lion enclosure closed for the investigation. Zoo officials said the facility was safe, and what happened was the result of one person's actions in violation of zoo protocols.

Chilean police officials described the victim as a 20-year-old male, referring to him as a "frustrated man."

An investigation is underway.