Sydney, one of Australia's largest cities, recorded its deadliest day of the pandemic Monday. The capital of New South Wales has become the epicenter of the nation's third wave of COVID-19.

According to official data, the city detected 478 new COVID-19 infections Monday, its highest daily case count since the pandemic began. In response to the rise in new cases, the government has dispatched troops and police at key roads going into the city.

Sydney is now entering its eighth week of lockdown. New South Wales state Premier Gladys Berejiklian said the rate of transmissions in Sydney is "disturbingly high." She also confirmed that seven people died in Sydney because of the virus, including a 15-year-old boy with pneumococcal meningitis.

"Every death is a person who has loved ones, who has died in tragic circumstances," Berejiklian said.

To better enforce existing lockdown rules, more than 200 military personnel have been deployed across Sydney. The troops have been instructed to set up roadblocks in areas with the most COVID-19 cases. Authorities said the deployment of troops was necessary given reports of people constantly violating movement restrictions and social distancing rules in the city.

Only about 26% of Sydney residents aged 16 and above have been fully vaccinated. Health experts said Australia's unvaccinated population is vulnerable to the rapid spread of the more contagious Delta variant of the coronavirus.

Apart from Sydney, the Australian government will also be placing Melbourne, Darwin, and Canberra under strict lockdown starting Monday.

Victoria state Premier Daniel Andrews said he would be enforcing a nightly curfew, and the lockdowns put in place will remain until Sept 2. Andrews said the measures are necessary as the country is now at a "tipping point" in its fight against the disease. He said there was simply no other option but to enforce lockdown rules strongly.

Some officials have blamed the recent rise in COVID-19 cases on the complacency of some residents and those that have continued to break lockdown rules. Meanwhile, some have blamed Prime Minister Scott Morrison's government for its slow vaccine rollout. A poll conducted last week showed Morrison's approval rating drop to its lowest level since the start of the pandemic.

On Sunday, Morrison said the government has already ordered an additional 1 million doses of Pfizer's COVID-19 vaccine. He said half of the vaccines would be given to 20- to 39-year-olds in heavily affected cities like Sydney and Melbourne.