Firefighters heading to the Glen Forrest bushfire last night had a rock thrown through their windscreen.
The crew was travelling on Roe Highway in Beckenham when a large rock smashed through the front windscreen about 8.45pm.
It is believed someone dropped the rock from the Albany Highway overpass.
A police spokesman confirmed another car was also targeted and officers had taken photos of the damage to both vehicles.
A Department of Fire and Emergency Services spokesman said whoever threw the rock had stopped the crew reaching the fire. The truck was brought back to Maddington fire station for repairs.
Firefighters and helitacs battled the Glen Forrest blaze from just after 2pm yesterday and had to protect several homes and a primary school.
The fire started near Hardey Road and is now contained and under control, however this morning a bushfire advice remains in place ahead of a forecast gusty winds and fears the fire may flare.
Yesterday afternoon Glenburn Road resident Deanne Parker grabbed her dogs and left her house when she saw smoke and flames ripping through the valley.
"I don't think you ever get used to a bushfire," she said, praising the quick actions of fire crews.
Supt Allen Riley, the Department of Fire and Emergency Services incident controller, said 100 career and volunteer firefighters, with the help of water-bombing aircraft, had battled the blaze as it raced through 30ha of bush.
Glen Forrest Primary School principal Jan Applin said classes were finishing for the day when authorities asked them to move the 290 students to a safer area.
Many parents managed to pick up their children despite roadblocks. Mrs Applin said police escorted the rest of the students and teachers to M.J. Morgan Reserve.