LAS VEGAS (KLAS) — For the third time since April, a dolphin on display at the Mirage’s Secret Garden & Dolphin Habitat has died, the Strip property said Sunday.

“Incredibly sad news to share,” said Mirage spokesman Brian Ahern in an email Sunday announcing the death of K2, an 11-year-old bottlenose dolphin. Ahern said the facility is temporarily closed.

In a letter that also was sent to employees, Mirage Interim President Franz Kallao said the dolphin died Saturday and had been receiving treatment for a respiratory illness. “All of us are heartbroken over this tragic loss, especially our amazing animal health and care teams who love and care for our animals on a daily basis.”

Kallao said in the letter the property is “working closely with veterinary and pathology experts to determine the cause of death. We are also working with additional outside veterinary, water quality, behavioral, animal welfare, and environmental experts to help us conduct a thorough review and inspection of both the animals and the facility.”

On Sept. 2, the Mirage said Maverick, 19, a bottlenose dolphin at the same facility died after being treated for a lung infection.

In April, Bella, 13, another bottlenose dolphin at the resort, died after receiving treatment for several months for gastroenteritis, according to MGM.

Wild bottlenose dolphins typically have lifespans of 40 to 60 years, according to the National Marine Fisheries Service.