Ferocious winds tore through parts of northern Bangladesh flattening villages, uprooting trees and killing at least 55 people, police said on Thursday.
Thousands of people were injured in the Wednesday night storm and officials said the death toll could rise as many people were fighting for their lives in hospital. Hundreds of people were injured by flying debris, police said.
"The storm left a trail of destruction within minutes," said Imrul Chaudhry, an administrator in Mymensingh, 130 km (80 miles) from Dhaka. Mymensingh and Netrokona were the worst-hit districts.
Officials supervising rescue and relief efforts said the scale of destruction suggested the wind speed could have been more than 250 kph (150 mph) and the Dhaka meteorology office said the storm was probably a tornado.
"Given the ferocity and speed, we believe it was a tornado that forms on land suddenly and is impossible to forecast," one official said.
Storms and tornadoes are common in densely populated Bangladesh during the hot season, sometimes killing hundreds of people. The Wednesday storm was this season's first.
"Never before have I seen such havoc," said Bijoy, a 40-year-old government employee in Netrokona.
"I saw thick clouds covering the sky at around 7 pm (1300 GMT) and then heard a whistle-like sound. In a few minutes everything was destroyed," he said.
"People were crying out for help in the darkness."
Rescue workers were digging through piles of debris in devastated villages where many people were feared trapped in collapsed houses and under uprooted trees.
At least 20 villages were affected in Netrokona district, reporters in the area said. In some villages, not a single house was left standing.
The winds sucked up fish from ponds, killed cattle and damaged crops, witnesses said.
"Even brick-built houses were flattened, cycles flew in the air like toys and hundreds of acres of rice paddy were damaged," one reporter said after visiting some of the villages.
Government and private agencies have started sending food and other emergency supplies to the affected villages, officials said.
"The number of injured may cross 2,000 and at least half of them will need hospital treatment," Abdul Kader, a Netrokona official, said by telephone.
"But resources in the hospitals are already stretched and they will find it hard to cope with more patients," he said.
A private television channel put the number of injured at about 5,000.