MELBOURNE, Australia — The city that was once Australia’s worst COVID-19 hot spot on Thursday announced a seven-day lockdown, its fourth since the pandemic began.

The lockdown for Melbourne and the rest of Victoria state comes after a new cluster in the city rose to 26 infections, including a person who was in intensive care.

Victoria Acting Premier James Merlino said: “Unless something changes, this will be increasingly uncontrollable.”

The new Melbourne cluster was found after a traveler from India became infected with a more contagious variant of the virus while in hotel quarantine in South Australia state earlier this month. The traveler was not diagnosed until he returned home to Melbourne.

Australia’s second largest city last year underwent a second wave of infections that peaked at 725 new cases in a single August day at a time when community spread had been virtually eliminated elsewhere in the country.

That lockdown lasted for 111 days. A third lockdown that lasted for five days in February was triggered by a cluster of 13 cases linked to hotel quarantine near Melbourne Airport.

Victoria accounts for 820 of Australia’s 910 coronavirus deaths during the pandemic.