The earthquake occurred 8 km from the town of Petit Trou-de-Nep, about 150 km west of the capital, Port-au-Prince, at a depth of 10 km.
The earthquake left hundreds of people missing; According to the authorities in Haiti.
The Euro-Mediterranean Seismological Center said another 5.9-magnitude earthquake hit Haiti late on Saturday, hours after a major earthquake in the region killed more than 300 people.
The Euro-Mediterranean Seismological Center said the latest earthquake was at a depth of 8 km.
The earthquake was followed by a series of aftershocks.
On Saturday afternoon, the agency added on Twitter that rescue workers and pedestrians were able to pull many people out of the rubble.
The quake was felt as far away as Cuba and Jamaica, and was larger and shallower than the 7.0-magnitude quake 11 years ago that killed tens of thousands of people in the poorest country in the Americas.
But this earthquake occurred far from the capital at 8.30 am local time.
The nearest large town to the epicenter was Li Kai, with a population of about 126,000; where many buildings collapsed, or suffered severe damage; This is according to what the authorities said, who stated that they are searching for survivors under the rubble.
Prime Minister Ariel Henry declared a month-long state of emergency and pushed for faster aid to reach areas where towns have been devastated and hospitals are overcrowded with incoming patients.
He noted that some towns were almost completely destroyed, and that the government had people in the coastal town of Les Cayes to help plan and coordinate the response.
Henry continued, "The most important thing is to get as many survivors as possible under the rubble... We've learned that local hospitals - especially Les Cayes - are overcrowded," according to the Associated Press.
He also explained that the International Red Cross and hospitals in unaffected areas were helping to care for the wounded, and appealed to Haitians for unity.
"The needs are enormous," he said. "We must take care of the wounded... and also provide food, aid, temporary shelter and psychological support."