San Diego, California - Several gorillas at the San Diego Zoo Safari Park have tested positive for the coronavirus, marking the first known case of transmission to apes, the zoo announced on Monday.

Laboratory analysis of fecal samples collected January 6 from one of two gorillas seen coughing detected the infection with the virus.

As many as eight gorillas at the San Diego Zoo are believed to have contracted Covid-19. Three among them have shown symptoms.

Officials aren't ruling out the possibility that more animals have been infected.

Cats Cat's tragic secret uncovered by X-ray – how could he live like that?

The gorillas are now being quarantined together. Despite some coughing and other minor symptoms, they are "doing well" as they are eating and drinking as usual.

"We are hopeful for a full recovery," executive director Lisa Peterson said.

Experts believe the park’s staff brought in the virus unknowingly, as they were asymptomatic at the time and wore masks around the animals.

The zoo has been closed since December 6.

Wildlife experts are concerned about the new human to animal transmission, as gorillas are an endangered species and share 98% of their DNA with humans.