A SEVERE thunderstorm forced a cargo ship to break its mooring and smash into the Fremantle rail bridge overnight.
The storm, which hit the city just before 10pm last night, brought heavy rain to much of the South West and the city, and blacked out 20,000 homes.
Destructive winds were recorded in the South West, with Busselton Jetty recording a gust of 120km/h at 7.30pm.
More than 30 State Emergency Service and 20 Career and Volunteer Fire and Rescue Service personnel from Bunbury, Australind and Harvey units worked through the night responding to calls for help from storm damage.
Trains between Fremantle and Perth have been cancelled whilst the bridge is assessed for damage.