Families flee as bushfire rages

A bushfire emergency has been declared in the Lower Blue Mountains, where the towns of Warrimoo and Blaxland are under threat from fire fronts and ember attacks.

Aerial waterbombing is underway, and dozens of rural fire crews are on the ground.

In one street, residents have been warned to leave their houses, while earlier two schools took emergency action to protect their young students.

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As temperatures soared and winds hit 50 kilometres an hour.

The wall of flames sprang up in the early afternoon, seemingly from nowhere.

The choppers were ready, with the noise alerting parents who raced to Warrimoo Public School.

"All the kids are in the hall they're all safe in there, they've got them all playing games, singing along," Danny Tomea said.

But with the flames raging, extra fire crews were ordered in and the decision was made to get a bus to the school to move the children, who were starting to get frightened.

"It was scary, and it upset cause me and my friends kept crying," one student told 7News.

By now the blaze was starting to move, embers carried by hot winds were pushing the firefront from Warrimoo towards Blaxland.

On the ground firefighters were waiting and organising - they have known for some time that today was going to be full of danger.

The forecast was right - but there is no predicting how bad it will get.

"If it gets across the creek that it's going to give us a problem," Duncan Allan from the RFS said.

The fire was upgraded to emergency level and the order given to evacuate local residents, and Blaxland Public School.

As fire trucks rolled on to the school grounds, parents and children quickly left. Buses were brought in to make sure everyone got out.

It is now believed the fire might have been sparked by a common cause - power lines.

"When we arrived we found a large area of bush alight under high tension power lines," Fire & Rescue NSW's Bruce Cameron said.

Because the fire is in such difficult terrain water bombing is the best option.

And while a cool change is on the way there are fears it will bring new dangers.