Lafayette | More than 500,000 residents in Louisiana and Texas were urged to flee their homes on Wednesday (Thursday AEST) as Hurricane Laura roared towards the Gulf Coast, fuelling grave warnings the storm would deliver a calamitous assault with powerful winds and a storm surge meteorologists declared "unsurvivable".

Laura intensified into a category-four hurricane as it churned through the warm waters of the Gulf of Mexico, growing into a monster of a storm that forecasters described as one of the worst to pound the region in decades.