Four lions at Barcelona Zoo have tested positive for COVID-19, veterinary authorities said on Tuesday. 

According to Australian Broadcasting Corporation, three females named Zala, Nima and Run Run, along with male Kiumbe, were tested after keepers noticed they showed slight symptoms of coronavirus.

Two staff at the zoo also tested positive for COVID-19, authorities said, after the outbreak was first detected last month. Authorities are investigating how the lions became infected.

Keepers carried out PCR tests on the lions in the same way as humans are tested as the animals are accustomed to contact with the zoo staff.

The Veterinary Service of Barcelona contacted colleagues at the Bronx Zoo in New York, where four tigers and three lions tested positive for COVID-19 in April.

It is the only other zoo where large felines are known to have contracted coronavirus. All recovered.