Tropical Cyclone Heidi slammed into northwestern Australia as a Category 2 storm early Thursday morning, dousing the region with torrential rain as residents remained on "red alert" over reports of strong winds and flooding, officials said.

The storm system, which prompted several major ports and oil fields to shut down in anticipation of tidal surges, packed gales of up to 145 kilometers per hour (90 mph) as it headed inland, according to Neil Bennett, a spokesman for the country's Bureau of Meteorology.

It has since weakened to a Category 1 storm and continues to lose steam as it moves farther inland, Bennett said.

Several sea ports were shut down ahead of the storm, from Port Hedland - a major iron ore exporting center - down to the more southern terminals at Dampier, according to Steed Farrell, a spokesman for the Port Hedland Port Authority.

"It's in the hands of mother nature," he added.

The agency activated contingency plans, which removed all nonessential personnel from the ports and obliged major vessels to relocate.

Some 3,600 residents in the Port Hedland area were left without power Thursday after the storm rolled through, according to the region's electricity provider, Horizon Power.

The country's largest oil and gas firm, Woodside Petroleum, also closed operations in several offshore oil fields.