Australian Capital Territory (ACT) officials have declared a state of emergency as major bushfires rage in the south of Canberra.

It is the worst fire threat to the city in almost two decades, officials said. The largest wildfire, in the south of the country, burns on over 18,500 hectares.

Residents in Canberra suburbs have been urged to “remain alert” about possible evacuations.

“The ACT is now facing the worst bushfire threat since the devastating fires of 2003,” Chief Minister Andrew Barr told media sources on Friday.

“There’s now no higher priority for the ACT government at this time than the bushfire threat.”

Located between Sydney and Melbourne, this tiny area has about 400,000 inhabitants.

In 2003, bushfires killed four people in the Canberra suburbs, wounded another 500 and destroyed or damaged 470 houses.

On Friday similar weather conditions were recorded, authorities said. Mr Barr warned the fires as temperatures rose to 40C and were fueled by strong winds “may become uncontrollable.”

He said the worst blaze was just south of Tuggeranong city, in Canberra, a 20-minute drive south of Parliament House. He added that the state of emergency-which gives the fire authorities additional power and resources-would be in effect “as long as Canberra is in danger.”

Fires have raged for weeks near the town. Canberra’s airport was shut down last Thursday when a wildfire threatened to break its perimeter.

Three US firefighters died the same day after their plane crashed in the Snowy Mountains area over a fire zone near the city.