Young WA mum killed in crash

A young West Australian mother of three has died and her children were injured when her car crashed into a road train.

Her car collided head-on with a road train on the Great Northern Highway on Wednesday night.

The 24-year-old woman from Meekatharra died after being freed from the car in Mount Magnet in the state's mid-west.

Her three small children, aged seven, five and one and the 56-year-old male truck driver were were all injured.

There was another fatality when a motorbike rider in his 30s was killed in Perth early Thursday morning, making the first death of the Easter period.

Police say they will flood roads around Perth and holiday destinations and extra speed cameras and booze buses will be stationed in country areas to try to prevent accidents over the four-day long weekend.

There is pressure to stop a repeat of the horror Labour Day long weekend earlier this month when there were 11 fatalities on country roads.

The four days of Easter were the busiest time of the year on the state's roads and therefore the greatest risk for a crash, Police and Road Safety Minister Liza Harvey said.

"My message to motorists is to drive defensively. Not only do you need to have road safety at the front of mind throughout your entire journey, you need to expect that other drivers might not do the right thing," she said.

Double demerit points apply over the weekend.