Two young motorcyclists have been hospitalised after sustaining serious injuries during a crash in Perth’s northern suburbs on Friday night.

The crash happened about 9pm, when two Yamaha road motorcycles were travelling together in a westerly direction on Marangaroo Drive near Mirrabooka Avenue in Girrawheen.

Both riders, aged 19 and 20-years-old, lost control of their motorcycles by unknown means and fell onto the road.

Both sustained serious injuries and were taken to Royal Perth Hospital for treatment.

WA Police are asking people who may have witnessed the crash to come forward with CCTV or dashcam vision of the motorcycles travelling in the area between 8.30pm and 9.15pm.

Anyone with information is urged to contact Crime Stoppers online via www.crimestopperswa.com.au or by calling 1800 333 000.

It comes as WA Police reminded the community that double demerits will be in force for the upcoming WA Day long weekend until 11.59pm on Monday June 1.

“Police will be out in force right across Western Australia during this period, with officers highly visible and operating anywhere, anytime,” a spokesman said.