Warnings have been issued for people to stay safe amid the storm that is sweeping through Perth and the coast from Lancelin to Mandurah as lightning hit its fourth victim today.

The victim who was hit by a lightning around 4am was reportedly brought to Rockingham Hospital. Earlier, another person was struck by lightning in Welshpool.
Earlier, a person was hit by lightning at 4am on Wyeree Road in Mandurah and was taken to Peel Health Campus, while the second victim was struck at 4:30am on Brennan Promenade in Baldivis.

A third person was taken to hospital after he was struck at about 9am.

The storm resulted in the black out of at least 22,000 homes, mostly in the south metropolitan region, while domestic and international flights have been delayed.

Storm-related signal problems which emerged around Cockburn Central Station also caused delays on the Mandurah to Perth railway line, however, train services were back by lunchtime.

The Bureau of Meteorology has advised residents of a continuing risk of severe thunderstorms today, particularly in the south and east. Heavy rainfall, flash flooding and damaging winds were expected.

"If you live between Minilya, Mount Augustus, Paynes Find, Corrigin, Narrogin, Mandurah, along the coast to Dongara and inland to Minilya, including the Perth metropolitan area, you should take action with more dangerous weather to come," FESA said.

"This type of weather is not unusual however it could cause damage to homes and make travel dangerous," it added.

FESA's State Emergency Service said to be safe, people should close curtains and blinds, and stay inside. Also, the authorities advised the unplugging of electric appliances and not using landline telephones when there are lightnings.

The FESA added that if caught outside the house, try to find a safe place away from trees and powerlines, storm water drains and streams. If boating, swimming or surfing, immediately leave the water; and if there is flooding, make sandbags using pillow cases filled with sand and place them in the doorstep to protect your home.