Three killed in separate crashes in WA

Three people have been killed and another is seriously injured after three separate crashes in Western Australia over the weekend.

Police said a 45-year-old man was trapped in his car after smashing into a house in Gnowangerup, in WA's Great Southern region, about 10.30pm on Sunday and died from his injuries.

Significant damage was caused to the home but no one inside was injured.

Earlier in the evening, a 53-year-old motorcyclist was killed after crashing head-on into a car in Serpentine, southeast of Perth, about 6pm.

The driver of the car, a 26-year-old man, suffered a serious injury to his arm and was taken to hospital.

A 26-year-old woman, four-year-old girl and 11-month-old boy were also in the car but were not injured.

In a third crash, a 70-year-old man died after his ute struck a tree near Trayning, in the state's Wheatbelt region, on Saturday about 3.30pm.