A fire in Perth's south that forced the evacuation of the Waldorf School in Bibra Lake is brought under control, with authorities downgrading the warning level to an advice.

Waterbombers as well as fire crews on the ground tackled the blaze.

A watch and act warning alert had been issued for the southern part of Coolbellup for people bounded by Sudlow Road, Phoenix Road, North Lake Road, the Roe Highway Extension and Progress Drive.



A number of roads in the area were closed.

Father Udo Scholtyssek said he rushed to the Waldorf School to pick up his son Harry when he realised where the fire was.

"I just saw smoke coming our way... and I jumped on my bike and I thought I'd better rescue my boy," he said.

"I wanted to walk through here but the police wouldn't let me, I guess they have to do their job but who can hold back a Dad on a rescue mission?

"I somehow made my way to the school, and lucky the fire didn't escalate and we're all good now."

The cause of the fire remains unknown.