Looting is a "serious" problem on the Dutch part of the hurricane-hit island of St Martin, with troops seeking to restore order, Dutch Prime Minister Mark Rutte said Friday.

"The situation is serious," he said when asked about looting, adding that authorities were being hampered in dealing with it as communications were cut off when Hurricane Irma roared through on Wednesday.

Extra troops and police are arriving on the southern part of the island, which is shared between France and the Netherlands, and part of their job is to help keep order, officials said.

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.

"We will not abandon Sint Maarten," he said, adding that officials were also sending medicines, tents, tarpaulins 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.

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

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

Dutch officials have confirmed that one person was killed on the Dutch part of Saint Martin by the Category Five storm, before it was downgraded early Friday to a four as it barrelled towards Cuba and Florida.