Smoke is seen in New Zealand as Sydney region faces a catastrophic threat.

Thousands of people are in the path of deadly Australian bushfires that have produced clouds of smoke seen as far away as New Zealand.

A seven-day state of emergency has been declared in New South Wales, where strong winds, high temperatures, and low humidity have prompted the Rural Fire Service to issue a “catastrophic” fire warning for the greater Sydney region.

It’s the worst threat level ever issued for Sydney under the current system, which was introduced in 2009.

The city is home to around 4.6 million people, but the greatest fire risk lies in rural areas outside the city center.

They include the greater Hunter area, Illawarra, and Shoalhaven, which are also facing “catastrophic” fire threats.

“Homes that are specifically designed and built to withstand bushfires are not done so for catastrophic conditions.

Catastrophic conditions are where lives are lost, it’s where people die. The risks are absolutely real,” New South Wales Rural Fire Commissioner Shane Fitzsimmons said.

As of Monday afternoon, more than 70 fires were burning across New South Wales, the fire service said.

A state-wide fire ban will remain in place on Tuesday, preventing people from lighting open fires and engaging in activities that could start a fire, like welding and grinding. Offenders risk on-the-spot fines of 2,200 Australian dollars ($1,500).

Hundreds of schools in fire risk regions will be closed on Tuesday, according to local media. As of late Monday, around 50 fires were raging across the northern state of Queensland.

Australia is experiencing one of its worst droughts in decades. The hot, dry weather has created a huge amount of fuel for the fires, which are being fanned by strong winds.

“In catastrophic circumstances, routinely, you can expect the most extraordinary of fire behavior.

It is not without question that spotting activity can be well and truly over 20 kilometers (12 miles) ahead of the main fire front,” Fitzsimmons said. Spotting refers to new fires lit by burning embers.

A “catastrophic” threat calls on people to evacuate ahead of time: “For your survival, leaving early is the only option,” the warning states. “The damage so far has been significant”.

Three people have been killed in the blazes and more than 100 homes have been lost. An estimated 350 koalas died in the fires and at least a dozen are being treated for injuries.

Satellite images showed smoke billowing more than 4,000 kilometers (2,500 miles) across the Tasman Sea to New Zealand’s South Island.