A detachment of 68 firefighters from the island of Martinique and Guyana on the South American continent arrived in Dominica on Thursday.
At least 15 people died and about 20 were still missing when the aid arrived.
Maria caused extensive damage to homes, road and forests on the small, English-speaking island, which has a population of 72,000.
It also hit the French island of Guadeloupe, killing two people there.
The French government representative in Martinique, Patrick Amoussou-Adéblé, who visited Dominica with the territory's president, Alfred Marie-Jeanne, promised that more aid would follow.
"We have carried out reconnaissance missions in helicopters to evaluate things," he said.
A French navy warship that could deliver equipment and 40 tonnes of water was also present, he added.
The whole island suffered from the effects of the hurricane, which was at its most intense on 18 September, according to Prime Minister Roosevelt Skerrit.
Some villages are only accessible by helicopter or from the sea.