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(CNN) -- More than 170,000 homes are without power in Queensland after a massive cyclone slammed into the already flood-ravaged northern Australian state, according to the emergency services minister. Some areas could be without power for weeks.
Neil Roberts told CNN that said that no serious injuries have been reported since Tropical Cyclone Yasi roared ashore, but emergency crews are still working their way across the affected region.
So far, the worst-hit towns seem to be in an area roughly 90 miles (150 kilometers) south of Cairns, he said.
Queensland Premier Anna Bligh described conditions for local TV networks, and said that many coastal cities are enduring power outages. In Cairns, only 34% of homes had electricity. Townsville, south of Cairns, only has power in about 15% of homes. Farther down the Queensland coast, electricity is out in half of Mackay and Proserpine, and the entire town of Ingham was without power.
Bligh said the tens of thousands of power outages were caused by downed lines and a transmission break. Electrical supply lines running into coastal communities have been cut south of the town of Innisfail.
"It is not clear yet why it has been cut and we won't know until we are able to get into the air and check all along that system," Bligh said. "I should say that requires checking 400 kilometers (248 miles) of line and 500 transmission towers."
It could take weeks to repair the problems, Bligh said, an assessment affirmed by Queensland's emergency services minister.
Tropical Cyclone Yasi is now a Category 2 storm, significantly diminished but still able to bring strong winds and heavy rain into interior areas of the country, according to CNN meteorologist Jenny Harrison. Yasi is moving toward the west. Wind speeds could reach up to 77 miles per hour (125 kilometers per hour) and very heavy rains could cause localized flooding Thursday and in days to come, she said.
Joe Vella, a resident of Cairns, said that wind gusts when Yasi came ashore sounded like a sledgehammer hitting his house -- and that it went on for four hours. "Our hearts were in our throats thinking what was going to happen," he told CNN.
Tropical Cyclone Yasi made landfall late on Wednesday night, local time, as powerful Category 5 storm, the highest designation on Australia's classification system.
Thousands of people left their homes ahead of the storm, which forecasters warned was one of the worst the country has ever seen.
Earlier, Queensland's Premier, Anna Bligh, warned residents they may have to cope alone for several days.
"I can't sugarcoat this for people. It's going to be a tough 24 hours. For some it's going to be a tough couple of days," she said at a news conference. "They need to prepare for the worst-case scenario, and that might mean they have to be self-sufficient for a couple of days.
Carl Butcher, another Cairns resident, said before the storm, "I have all my rations ready to go, batteries, candles. The authorities have been very proactive in informing us about this system. We have known about it for a week. That is more than enough time to prepare for it."
CNN Meteorologist Jennifer Delgado said heavy rain in Queensland could continue until Friday.
There are serious concerns for six adults in Port Hinchinbrook, who apparently ignored advice to evacuate the storm surge zone before calling to request help from the emergency services. Police, who are in contact with them via telephone, said the group are currently hunkered down on the second floor of an apartment block, but the tidal surge is expected to reach the top of the first floor.
The state's premier, Anna Bligh, had urged residents in the threatened areas to take sensible precautions and to stay inside once the storm hit.
"It will be a display of the awesome power of nature, but it is not something you want to go outside and watch," she said.
The cyclone threatens more devastation for Queensland, where 20 people died and thousands of homes were wrecked in severe flooding in January, which affected 3.1 million people.
Australian Prime Minister Julia Gillard has announced a one-off tax aimed at helping to for pay the estimated AUS $5.6 billion (US $5.58 billion) in damage caused by that flood.
CNN's Pauline Chiou, Hilary Whiteman and Bryony Jones contributed to this report.