Firefighters have contained a bushfire burning in the northern Perth suburb of Joondalup that caused the evacuation of a university campus and damaged two buildings.

The fire, which had been burning in an area to the east of the Edith Cowan University [ECU] residential campus, has been downgraded from an emergency warning to advice level.

Hundreds of staff, students and children had earlier been evacuated from the campus, including from the university's childcare centre.

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The campus was closed and all classes cancelled for the rest of the evening.

A house in Grassbird Avenue across the road from ECU was badly damaged by fire, as was an accommodation building on the university campus.

DFES said the fire was contained but not yet controlled, and about 80 firefighters were still at the scene strengthening containment lines.

A number of roads in the area remain closed.

Firefighters suffering from heat exposure, exhaustion

Six firefighters have reportedly needed medical attention.

DFES spokesman Alan Gale said 21 hectares had been burnt and two buildings damaged.

"I think the house is extensively damaged," he said.

"[A number of] firefighters are suffering from heat exposure, heat exhaustion.

"The ambulance has been busy treating firefighters that have been injured."

He said the fire was being treated as suspicious and the police arson squad was in attendance.

Weather conditions have not helped.

"It was moving very fast fanned by these strong hot easterlies burning from the north-east," he said.

The temperature in Perth reached a high of 39.8 degrees Celsius at 4:10pm, while at Hillarys, near Joondalup, it was 39.8C at 4:44pm.