At least 242 people have been reported dead after a powerful cyclone battered southern Bangladesh, levelling villages and uprooting trees. Officials have warned that the death toll could rise and that the extent of the damage is still unclear.
Hundreds of thousands of people were evacuated or sought safe shelter before the storm hit the coast, but some were left behind.
The storm was weakening early Friday as it passed through the capital, Dhaka.
With the worst of the storm thought to be over, attention now turns to assessing the damage and distributing aid, the BBC's Mark Dummett reports from Dhaka.
The World Food Programme is send emergency food rations for 400,000 people. The government, the Red Crescent and other NGOs are also sending teams.
However, our correspondent says that Dhaka's main airport has suspended operations, river ferries are not running, roads are blocked by uprooted trees and electricity supplies have been severely disrupted.
Communications down
The damage from Cyclone Sidr was worst on Bangladesh's southern coastal strip.
The Home Ministry in Dhaka said several districts could still not be contacted as telephones and communications were cut and reports of casualties were confused.
Nahid Sultana, an official from the Ministry of Relief and Disaster Management, confirmed the death toll and said it was likely to rise.
Many people are thought to have been killed as falling trees flattened fragile houses. In one case, an elderly man drowned when a small boat capsized, the AFP news agency reported.
Bangladeshi television said more than 100 fishing boats in the Bay of Bengal had failed to return to shore despite storm warnings, Reuters reported.
Red Crescent officials have said at least three villages were flattened by the storm.
Residents of the capital, Dhaka, told the BBC news website that buildings and roofs were shaken by fierce winds during the night, and that by morning power and water supplies had been cut.
"All night the wind has been raging so hard that I thought my window will shatter," said K Ashequl Haque.
Search under way
Most ordinary houses in rural areas are made of thatch, wood and tin, and officials and local witnesses say many were easily flattened by the wind.
 | Click here for a detailed map of the affected region 
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"We have mounted a search by civilians, army and police, and the casualty figures will rise," an official in Barisal, one of the worst hit districts, told Reuters.
"We have been virtually blacked out all over the country," a disaster management official in southern Mongla, another badly affected area, told the agency.
The cyclone had roared in from the Bay of Bengal just before dusk on Thursday, generating winds of up to 240kph (150mph) and driving rain.
The storm swept through Dhaka overnight, where it pulled up trees and cut power.
The capital's airport was closed, and river ferries stopped running.
The cyclone was also expected to affect eastern India and the west coast of Burma.
More than 40,000 policemen, soldiers, coastguards and health workers have been deployed along the coast.
 Many people are taking cover in state-provided cyclone shelters |
Hundreds of thousands of coastal villagers have been evacuated, with thousands more moving into government-built cyclone shelters.
The cyclone triggered 5m (16ft) tidal surges in many of the affected districts, Reuters reported. Rivers flowing into the Bay of Bengal were said to be swollen and rising.
Authorities said they had sent food, medicine, tents and blankets to the affected areas.
Southern Bangladesh is often hit by cyclones, but experts say the latest one is a category four storm, the most powerful so far in the season.
Bangladesh developed a network of cyclone shelters and a storm early-warning system, after a cyclone killed more than 500,000 people in 1970.
Casualties from cyclones have been significantly reduced as a result, officials say.
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