New South Wales health officials interview passengers as they arrive from a Qantas flight that flew from Melbourne at Sydney Airport in July.

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James D. Morgan/Getty Images

New South Wales health officials interview passengers as they arrive from a Qantas flight that flew from Melbourne at Sydney Airport in July.

James D. Morgan/Getty Images

The border between Australian states Victoria and New South Wales will close because of a spike in coronavirus cases, officials announced on Monday.

Victoria Premier Daniel Andrews said the closure is for an undetermined period.

Victoria, whose capital city is Melbourne, has logged 127 confirmed cases in the last 24 hours, which accounts for more than 90% of Australia’s infections during that period, according to national data.

New South Wales Premier Gladys Berejiklian said that the border would first shut down to residents of Melbourne, where the outbreak has been concentrated, and then will extend to all residents of Victoria on Wednesday. Police and health officials will monitor 55 ground crossings — including highways, bridges and waterways — as well as airports and rail stations according to a report from ABC Australia.

“We wouldn’t have taken this step unless we absolutely had to,” Berejiklian said. “Please know this is not a decision we take lightly, but during the pandemic I have always said New South Wales will have a no-regrets policy.”

Several public housing projects have been put on lockdown because of the outbreaks around Melbourne. The Sydney Morning Herald reported that residents of nine public housing towers in the suburbs have been put on a lockdown after a spike in coronavirus cases.

Andrews promised to protect residents from financial hardship.

The decision to shut the border marks the first time since the 1919 Spanish Flu outbreak that officials have blocked movement between the two states. Victoria’s other border, with the state of South Australia, is already closed.