Dutch troops were fanning out across part of the hurricane-hit island of St Martin on Friday as shots were heard and officials admitted there had been some looting.

"The situation is serious," Dutch Prime Minister Mark Rutte said when asked about looting, adding authorities were being hampered in their efforts to deal with it as communications were cut off when Hurricane Irma roared through on Wednesday.

Shots had been heard on the island, a top marine official revealed, but said it was unclear where they had come from.

"Shots have been fired, but not in a structured fashion," Major General Richard Oppelaar, the commander of the Marine Corps, told reporters in The Hague.

"I can't deny there are some weapons around," he added, adding in some areas the situation remained "grim" and the atmosphere was tense.

"The supermarkets are empty, so people are out searching," Oppelaar said, adding in principle security was under control with soldiers trying "to be as visible" as possible.

About 200 Dutch soldiers have now arrived on the island, which is divided between France and The Netherlands, to help deliver aid and restore order, he added.

The badly damaged airport and port have now "been opened for military purposes," Rutte told reporters, adding "we are doing everything possible to get aid to the area."

He said food, water and security were the priorities on the island, known in Dutch as Sint Maarten.

"There are people on the streets armed with revolvers and machetes," one witness told the Dutch daily newspaper AD on Friday.

"The situation is very serious. No one is in charge."

"We will not abandon Sint Maarten," Rutte vowed, adding officials were also sending medicines, tents, tarpaulins, building materials and hygiene kits as fast as possible to the Caribbean.

"The military has two tasks after arriving there. Firstly to ensure that there is food and water, but also to ensure security," Rutte said.

Dutch officials have confirmed that two people were killed, and 43 wounded, 11 of them seriously, on the Dutch part of St Martin by the Category Five storm, before it was downgraded Friday to a four as it barrelled towards Cuba and Florida.

King Willem-Alexander is to visit Curacao on Sunday from where the Dutch aid operation is being coordinated, and may then travel on to Sint Maarten.

A fund launched by the Dutch Red Cross in the hours after the storm pummelled the island as already raised some 850,000 euros for the Dutch territory.

jkb-cvo/ach