Chessington World of Adventures has launched an investigation after its population of capybaras suddenly died last month.
Guests to the family-friendly zoo wanting to take part in a feeding session were left distraught when told the rodents had passed away.
The popular zoo has no plans to bring in new ones until the mystery surrounding their deaths has been solved.
Messages of heartbreak and confusion outpoured on social media.
One capybara-lover lamented: "When was someone going to tell me the capybaras died at Chessington?
"I'm going to go cry now."
Another mourned: "The capybaras at Chessington are dead and I feel really sad about it."
One said: “Very sad to hear the capybaras at Chessington zoo have passed away.
“They are very lovely animals and I can't say I'm anything short of distraught. Rest in peace to the little fellas.
“It's sad news indeed.”
The zoo was first opened in 1931 and has over 1,000 animals including gorillas, tigers and sea lions.
Capybara-lovers were sent into panic when the zoo's feeding experience with the pig-like animals was axed.
Fans used to be given 20 minutes in the enclosure feeding and petting the animals.
A spokesman said: "It is with great sadness that we can confirm the death of our three capybaras.
"External veterinary experts are working closely with our dedicated welfare team to conduct a thorough investigation into why the animals sadly passed away.
"This investigation remains ongoing and until we know the results, we wouldn't be making any decisions on bringing new capybaras in.
"We know our capybaras are extremely popular with our guests, and were much loved by all of us here, especially our dedicated zoo team."
"The health, safety and welfare of our animals is the primary concern to us here at Chessington World of Adventures Resort.
"We are a member of EAZA (European Association of Zoos and Aquariums) and BIAZA (British and Irish Association of Zoos and Aquariums).
"Both of which have strict codes of practice and ethics covering animal management, conservation, education research and operations."
Capybaras are the world's biggest rodent and loved for their chunky snouts and friendliness towards humans.
They are native to South America and look like overgrown guinea pigs.
They became a hit at Chessington World of Adventures due to its feeding experience with them.
