Among the damaged buildings was a church in the northern town of Plaisance, the civil protection agency said, adding that additional food and medical supplies were on their way to the most battered towns.
Another four people died in and around the town of Gros-Morne further south, including a boy struck by a falling building, said mayor Jean Renel Tide.
At least 152 people were injured in Port-de-Paix and 30 wounded in Gros-Morne, said an unidentified local government representative. The epicentre of the quake was about 19 km, north-west of the city of Port-de-Paix.
Many wondered how they were going to rebuild from Saturday night's quake and a strong 5.2 magnitude aftershock on Sunday that had residents in the coastal city of Port-de-Paix and elsewhere anxious about returning to their cracked cinderblock homes for fear they would collapse.
A woman watching the scene, 49-year-old Rosette Jerome, said no one in her neighborhood had been killed "but a child was seriously injured when a piece of the wall fell on it".
A magnitude 5.9 quake struck off the coast of neighbouring Haiti late on Saturday.
Saturday's quake, which was felt across the country, struck at 8:10 pm (0010 GMT Sunday) at a shallow depth of 7.3 miles.
On Sunday, an aftershock of magnitude 5.2 hit the country, reported AP.
In 2016, Hurricane Matthew shredded parts of the country and left at least 336 people dead.
The Cuban ambassador to Haiti, Luis Castillo, confirmed to Prensa Latina that the embassy went undamaged. Some houses were destroyed, it said.
The town of Chansolme and the small island of Tortuga also suffered damage, officials said.
Impoverished Haiti, where many live in tenuous circumstances, is especially vulnerable to earthquakes.
Thousands of people along Haiti's north coast have dragged mattresses and chairs outside, fearing new aftershocks.
On January 12, 2010, Haiti suffered a devastating magnitude-7 natural disaster which killed more than 300,000 people and destroyed much of the capital Port-au-Prince.