DHAKA, Bangladesh (AP) -- A powerful cyclone slammed into Bangladesh on Thursday night, tearing down flimsy houses, toppling trees and power poles, and forcing hundreds of thousands to flee their homes in the low-lying nation.
Tropical Cyclone Sidr swept in from the Bay of Bengal packing winds of 149 mph (240 kilometers per hour), buffeting southwestern coastal areas within a 155-mile radius of its eye with heavy rain and storm surges predicted to reach 20 feet high.
Sidr's eye crossed the Khulna-Barisal coast near the Sundarbans mangrove forests around 9:30 p.m. (11:30 a.m. ET), the Bangladesh Meteorological Department said. It was centered over the Baleshwar River in Barguna district.
In the coastal districts of Bagerhat, Barisal and Bhola, residents said the storm flattened thousands of flimsy straw and mud huts, and uprooted trees and electric poles.
"We sitting out the storm by candlelight," resident Bishnu Prashad said by phone from Bagerhat.
At least 620,000 people had moved into official shelters and 3.2 million people were expected to be evacuated in all, said Ali Imam Majumder, a senior government official in Dhaka.
No casualties were immediately reported, but rescue teams were on standby, forest official Mozharul Islam said in Khulna.
Communications with remote forest areas and offshore islands were temporarily cut off.
"We have taken all precautions," Majumder said.
Bangladesh a low-lying delta nation, is prone to seasonal cyclones and floods that cause huge losses of life and property. The coastal area bordering eastern India is famous for the mangrove forests of the Sundarbans, a world heritage site that is home to rare Royal Bengal Tigers.
The Meteorological Department had put the country's three major maritime ports -- Chittagong, Mongla and Cox's Bazar -- on the highest level of alert.
Ferry service and flights were halted across the coastal region.
Ships were warned to return to shore. Volunteers helped evacuate villagers to cyclone shelters, built of concrete on raised pilings. Some took refuge in "mud forts" built along the coast to resist tidal surges.
Schools, mosques and other public buildings were also turned into makeshift shelters.
Many of the fishing boats in the region's coastal waters put down anchor at nearby shoals and islets that dot the South Asian country's shoreline.
The sea resort of Cox's Bazar was deserted after Wednesday's warning. Dozens of tourists were stranded in the offshore coral atoll of St. Martins as rough seas forced cruise boats and ships to stay ashore.