An aerial view shows flooded houses and buildings as a dam broke after the landfall of cyclone Amphan in Shyamnagar on Thursday. AFP

At least 80 people were killed in eastern India and Bangladesh after a powerful cyclone tore through both countries, a state chief minister said on Thursday.

The cyclone struck the state of West Bengal on Wednesday, devastating villages, tearing down power lines, and leaving large tracts of land under water.

A woman carries her son as she tries to protect him from heavy rain while they rush to a safer place, in Kolkata. Reuters

State Chief Minister Mamata Banerjee said the death toll stood at 72 with most caused by electrocution and falling trees.

Bangladesh officials said at least 10 people had died, including a five-year-old boy and a 75-year-old man both hit by falling trees and a cyclone emergency volunteer who drowned.

Residents walk along a house on a flooded street heading to a shelter home in Dacope of Khulna district on Wednesday. AFP

Millions were left without power after cyclone Amphan, packing winds of around 150 kilometres per hour, carried away electricity pylons, walls and roofs, officials said Thursday as they began to assess the damage.

A man walks in the rain ahead of Cyclone Amphan landfall, at Bhadrak district. AP

Residents in the Indian city of Kolkata, the capital of the hard-hit West Bengal state, awoke to flooded streets with some cars window-deep in water and television footage showed the airport inundated.

"The impact of Amphan is worse than coronavirus," Mamata Banerjee, chief minister of West Bengal, told local media, saying that at least 12 people had died in the state.

"Thousands of mud huts have been levelled, trees uprooted, roads washed away and crops destroyed," she said.

An aircraft is parked at the flooded Netaji Subhas Chandra Bose International Airport in Kolkata on Thursday. AFP

Officials said they were waiting for reports from the Sundarbans, a UNESCO World Heritage site famed for its mangrove forest and population of endangered Bengal tigers, which bore the brunt of the storm.

"We still haven't got the actual picture of the damage. We are particularly concerned over some wild animals. They can be washed away during a storm surge in high tide," forest chief Moyeen Uddin Khan told AFP.

cyclones are an annual and growing hazard along the Bay of Bengal coast, claiming the lives of hundreds of thousands of people in recent decades.

But in recent years, despite an increase in their frequency blamed partly on climate change, improved warning systems have enabled authorities to be much better prepared.

Agencies