The worst-affected island so far is Saint Martin, which is divided between the Netherlands and France, where eight of the 10 confirmed deaths took place.
Footage from a Dutch naval helicopter showed widespread devastation, with dozens of shipping containers overturned, buildings with roofs torn off, wrecked boats and debris flung far and wide.
“Lots of people are just wandering around aimlessly, as they have no homes any more and don’t know what to do,” local newspaper editor Paul de Windt told the Paradise FM radio station from the island, which is home to around 80,000 people.
“It’s catastrophic,” he added.
The airport on the Dutch side of St Martin has been destroyed and the harbour is also badly damaged, making it difficult for Dutch authorities to bring in supplies and rescue teams by air or sea.
French Interior Minister Gerard Collomb said that the airport on the French side had “not been hit so much,” allowing helicopters and eventually other aircraft to fly in 100,000 emergency rations, fresh water and equipment.
“The destruction is massive,” Collomb told reporters in Paris, with rescue efforts hampered by damage to the vehicles and buildings belonging to the local police and fire services.
Mobile telephone and electricity networks have also been knocked out.
– Isolated islands –
Around 200 French troops, rescuers, soldiers and medics as well as military helicopters and a transport plane, have flown to the Caribbean where efforts are being coordinated from the larger French island of Guadeloupe.
French President Emmanuel Macron will travel “as soon as possible” to the region, where the European-run islands are a legacy of colonialism.
The Dutch defence ministry had stationed two naval vessels in the area before the storm equipped with a helicopter and supplies, while two military planes and at least 100 soldiers are also involved in aid efforts.
“The priority now is to bring emergency aid to the people… consisting of sending food and water to 40,000 people over the coming five days,” Dutch Interior Minister Ronald Plasterk said.
British efforts are focused on trying reach the island of Anguilla, whose port and airport are both closed, according to Alan Duncan, a junior foreign minister.
“Anguilla received the hurricane’s full blast,” he told parliament, adding that the British Virgin Islands had also been hit, while the Turks and Caicos islands were next in line.
“The initial assessment is that the damage has been severe and in places critical,” he said of Anguilla.
The government set aside an initial £12 million (13 million euros, $15.5 million) for immediate relief and is sending a navy boat to help with rescue efforts.
– ‘Huge damage’ –
A day after the Category 5 hurricane smashed its way across St Martin, French teams are also heading for the much smaller nearby French island of St Barthelemy, also known as St Barts.
Rescue dogs have been flown in because “unfortunately there is work to be done on St Barts where the damage is very significant,” French Overseas Territories Minister Annick Girardin said.
St Barts, home to around 9,500 people, is known as a playground for the rich and famous including past visitors Beyonce, Steven Spielberg and Gwyneth Paltrow.
Speaking to broadcaster RTL, 20-year-old Koen who lives in the town of Voorhout on St Martin said he was shocked by the scenes which greeted him after the storm passed.
“There is huge damage. Sand has been blown over everything. Everything is destroyed,” he said.