"Most difficult time for me in 20 years", Richard Block from Santa Barbara Zoo said.
A 47-year-old elephant, brought the US from India in 1972, has been euthanized after it failed to respond to an array of medical treatments.
Sujatha, a popular animal at the Santa Barbara Zoo in California, is one of the two Asian elephants at the zoo. It came to the US as a one-year-old with another companion called Little Mac.
Zoo authorities have said it is an incredibly difficult time for them. "She had been a beloved member of the Santa Barbara community ever since it came here," CEO Rich Block said in a statement posted on the zoo's website.
"It is with broken hearts that we announce the passing of 47-year-old Sujatha, one of the Santa Barbara Zoo's two Asian elephants," Mr Block added.
Sujatha's health had been had been getting worse with age. "We employed an array of treatments to address her challenges and pain, including laser therapy, stem cell treatments, physical therapy, hydrotherapy and medications. In the last two weeks, her health began to decline. After exhausting all options to help Sujatha and following weeks of discussions, the difficult decision was made to humanely euthanise her last night," he added
Sujatha was very close to her keepers and Little Mac. It has delighted generations of families who met her and inspired countless numbers of individuals to care more about the world around them, zoo authorities.
"She has left her mark on this community and has helped us all be more conscious, more connected, and more inspired than we were before," Elephant Manager Liz Beem said.