Two men killed in separate WA crashes

A man has died and seven children are injured after their car crashed into a power pole in Perth's south.

Mandurah Road at Kwinana Beach was closed after the crash brought down power lines about 7.30pm on Saturday.

The 36-year-old driver died at the scene and the seven children, aged between three and 14, were treated for minor injuries by paramedics before being taken to Rockingham Hospital.

In a separate incident, a man was killed when his car smashed into a tree on Forrest Highway near Preston Beach, south of Perth, about 1.30am on Sunday.