Courtesy El Salvador Culture Ministry H/EPA Gustavito lies in his pool as workers try to save him from brutal attack.

UPDATE: Mar. 4 ― Gustavito the hippo may have died from insufficient care at El Salvador’s National Zoological Park, a post-mortem examination suggests.

Prosecutors say there were no puncture wounds on the animal’s body and he died from pulmonary hemorrhaging, or bleeding inside the lungs. However, officials were still not totally ruling out an attack as of Saturday.

PREVIOUSLY:

Authorities are investigating the savage beating of a hippo in El Salvador’s National Zoological Park, who died from his injuries days later.

Officials believe the hippopotamus, known as Gustavito, was attacked last Wednesday night in his San Salvador enclosure. No one was initially aware of his injuries until managers noticed the mammal was behaving strangely, not eating and spending long periods huddled in his pool of water, CNN reported Monday.

La dolorosa muerte de Gustavito, el único hipopótamo de El Salvador que murió por un "cobarde e inhumano" ataque https://t.co/8vRRtJRY2Y pic.twitter.com/j6QWpLBuQ0 — BBC Mundo (@bbcmundo) February 27, 2017

When veterinarians examined the animal, who was popular with zoo visitors, they found the 15-year-old was in “great distress.”

He had multiple wounds or bruising over much of his body, including his feet, neck, face, and even inside of his mouth, which likely occurred as he tried to defend himself, said zoo director Vladen Henríquez.

Officials believe he was attacked with rocks, metal bars, knives and an ice pick.

Workers spent 24 hours a day caring for him, but he died on Sunday.

Zoo officials called the attack on the Gustavito “cruel and inhumane,” and the Ministry of Justice has launched an investigation to find the attackers.

Gustavito had been at the zoo for 12 years after he was brought there from Guatemala, and was the park’s star attraction. Fans tweeted their sorrow at his death.

El Salvador is one of the world’s most violent countries, but the death of Gustavito was a particular low point for residents. “We’re used to seeing the dead every day,” a San Salvador street vendor told The Associated Press. “But this tops it all. They killed an animal that only entertained us.”

Whoever did this has to pay. My heart goes out to you and your keepers; may you rest in peace. #Gustavito #ElSalvador pic.twitter.com/h4SiVwasCk — Gigi Perla (@gigiips22) February 27, 2017

CORRECTION: A previous version of this article misstated that Gustavito came to El Salvador from Guam; he came from Guatemala.