The prime minister of the Bahamas says the islands are in their "hour of darkness" as conditions "rapidly" deteriorate six days after Hurricane Dorian.
Tens of thousands of people are homeless and it is estimated that around $3bn in insured property has been damaged in the Caribbean.
The official number of dead - 43 - is expected to rise as the situation becomes clearer.
After wreaking havoc in the US state of North Carolina, Dorian arrived on Canada's Atlantic coast on Saturday with heavy rain and powerful winds toppling a construction crane in Halifax and knocking out power for hundreds of thousands of people.
Bahamian Prime Minister Hubert Minnis said: "We acknowledge that there are many missing and that the number of deaths is expected to significantly increase.
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A number of countries are helping in the aid effort and have also donated cash towards the operation.
Cruise ships have also been helping to deliver supplies, health workers and emergency crews to the islands, and ferrying survivors to the US.
About 1,100 people who had been evacuated by ship arrived in Florida, weary but safe.