Witnesses in the northern Tangail district described seeing "a fire-red funnel" appear in the western sky seconds before the tornado struck.
It slammed into dozens of villages and obliterated them. Homeless survivors fled through a deadly whirlwind of flying tin roofs, torn-up trees and dust. Some people tried to save themselves by clinging to trees, but many of them died when the 125mph winds ripped them away.
The tornado lasted only 20 minutes, late on Monday afternoon. But its impact was fierce and deadly. The death toll is still climbing, as the army and rescue workers reach the devastated areas of this cotton-growing district. In one village 120 people were killed, many of them children who were crushed when the tornado destroyed a boarding school.
State-run Radio Bangladesh said that emergency aid was being rushed to the tornado-struck northern regions.
Witnesses told news agencies that buses full of injured people were arriving at hospitals. The injured were being carried to medical care from villages cut off by road in hammocks strung from bamboo poles.
It is the country's worst catastrophe since 200,000 Bangladeshis were killed in a storm in 1991.
Tornados are common in Bangladesh, as are floods and droughts. More storms are expected, and one of the country's main rivers, the Brahmaputra, is also in danger of flooding.
Most of Bangladesh is only a few feet above sea level and when the rivers flood, as they do often, much of Bangladesh is then swamped.
The storms sweeping up the Bay of Bengal also caused havoc in the Himalayas. At least eight climbers on Mount Everest were killed when a freak blizzard struck the world's highest mountain. The country's caretaker Prime Minister, Habibur Rahman, said emergency relief would be provided for the tens of thousands of victims left homeless and whose crops were ruined by the tornado.
More bodies are expected to be found today, when rescue workers reach many of the cut-off villages. Hospital workers reported that blood and bandages were running out, and even though the area of devastation was only 60 miles from the capital, Dhaka, uprooted electric poles and fallen trees had blocked the main roads.
A doctor quoted by news agencies, Rafiqul Islam Khan, said there were "scores of screaming patients lying on the hospital floor with more arriving constantly".