Parts of Sydney lock down as an outbreak grows in Australia’s biggest city.

The central business district and eastern suburbs of Sydney, Australia, will be locked down for at least a week after another daily surge in coronavirus cases linked to the Delta variant.

Officials in New South Wales, which includes Sydney and is Australia’s most populous state, announced an additional 22 cases on Friday, bringing the total number of cases to 65, the city’s largest outbreak in six months. They warned that many more cases were likely to emerge in the coming days because of a cluster centered on a hair salon that some 900 clients visited while several employees were infectious.

The lockdown will affect a large portion of Sydney’s five million residents since it applies to anyone who works in the city center. It comes on top of a return to mandatory mask wearing and a ban on travel outside the city, which were announced this week.

The new restrictions reflect a mix of widening concern about the infectiousness of the Delta variant — many of the confirmed infections appear to have occurred after only a few seconds of contact — and an effort to keep the outbreak contained.

Under the lockdown rules, anyone who works or lives in the affected areas must stay at home for all but essential activities, such as exercise and shopping for food. All businesses will be closed except those that provide essential services.

“We don’t want to see this situation linger for weeks,” the premier of New South Wales, Gladys Berejiklian, said on Friday. “We would like to see this situation end sooner rather than later.”

Officials are especially worried about a handful of possible superspreader locations, including a child’s birthday party last weekend where at least 17 attendees had tested positive as of Thursday evening. The rest of the people at the party are also expected to be infected, along with the household contacts of nearly everyone there.

The hair salon has the potential to add dozens or hundreds more cases. Everyone who passed through over the past several days has been asked to get tested and to isolate.