Cyclone Bulbul has ripped through coastal areas of Bangladesh and India, killing at least 13 people while more than two million others were forced to spend a night in storm shelters.
The storm packed winds of up to 120km/h (75 mph), injuring dozens and destroying thousands of homes.
Five of the six who lost their lives in Bangladesh were hit by falling trees.
Officials say that further casualties were avoided because people were evacuated in time.
Authorities say the storm is now weakening.
What damage did Cyclone Bulbul cause?
Seven people were killed in the Indian state of West Bengal, the state's minister for disaster management told reporters.
The five victims hit by trees in Bangladesh included a 52-year old woman who died when a tree dropped onto her house.
A 60-year-old fisherman also lost his life after ignoring evacuation warnings.
There are increasing concerns after two fishing boats carrying more than 30 men failed to return, an official in Bangladesh's Bhola district said.
Around 1,200 tourists, most of them Bangladeshi, were stuck on St Martin's Island, part of Cox's Bazar district, an official told the Reuters news agency.
"All of them will be rescued," he said.
Services at many sea ports and airports in the region were also suspended - including the busy Kolkata airport.
Bangladesh's two biggest ports, Mongla and Chittagong, were closed and flights into Chittagong airport were stopped.
Bangladesh's low-lying coast is often hit by deadly cyclones, but the country has successfully reduced the number of casualties in recent years.