A cyclist killed by a hit and run driver is the fourth person to die on WA's roads in 24 hours.

Police say the driver of a white ute collided with the 31-year-old cyclist on Kewdale Road near Dowd Street around 7.40am on Saturday.

Police rope off the scene of the Welshpool accident in which a cyclist was killed in a hit and run. Credit:WA Police

The driver didn't stop after hitting the rider, who's from Canning Vale, but about five minutes later the ute crashed off Roe Highway near Nicholson Road.

Police found the 38-year-old driver at the scene. He was taken to Armadale Hospital.