Philippe said around 50 people were injured, including two seriously, on St Martin and the nearby smaller island of St Barthelemy.
He said officials were in the process of identifying the four dead, adding that no deaths were reported from St Barthelemy.
On St Martin, 60 percent of homes have been damaged so badly that they are uninhabitable, said Philippe, describing the disaster as "unimaginable and unprecedented".
Power is cut across St Martin as well as supplies of potable water and petrol, he said. Roads are either partly or totally impassable, he added.
"The work will be long, emotions will run deep and the sadness will be great," he said.
One of the most powerful Atlantic storms on record, the rare Category 5 hurricane started its deadly rampage on Wednesday when it made landfall in Barbuda to the southeast.