Government spokesman Eddy Jackson Alexis told AFP news agency seven people were killed in Port-de-Paix, the capital of Haiti's Nord-Ouest department, while four others were killed in the town of Gros-Morne, about 50km to the southeast.
The USGS says the aftershock's epicenter was located 15.8 kilometres (9.8 miles) north-northwest of Port-de-Paix, and had a depth of 10 kilometres.
Government spokesman Eddy Jackson Alexis said that 11 people have been reported dead so far, the AFP news agency reported on October 7.
A crisis cabinet has been created to coordinate all emergency responses, Prime Minister Jean-Henry Ceant said in a statement posted to Twitter.
Authorities said more than 100 people were also injured when several buildings collapsed.
At least 11 people are dead and more than 100 were injured after a 5.9 magnitude quake hit the Caribbean nation of Haiti.
Google Pixel 3 preorders will start immediately after launch event
The search giant is referring to the Pixel Ultra as "mini Pixel". "Tune in on 10/9 to see for yourself", the company teased. The Google Pixel 3 is easily one of the most comprehensively leaked smartphones in the history of smartphones.
On Oct. 7, the Miami Herald, citing a local official, reported that 12 people had died, while adding that a number of buildings had been damaged.
The civil protection agency said early on Sunday that at least 135 people were being treated for injuries.
The agency said: "The shock was felt across all departments of the country, giving rise to panic in several towns".
The natural disaster was felt in the Haitian capital as well as in neighbouring Dominican Republic.
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". Tens of thousands of people are still displaced because of the natural disaster.
In 2010, a magnitude 7.1 tremor killed more than 250,000 people in Haiti.
The damage caused was worth an estimated 120 percent of GDP in Haiti, the poorest country in the western hemisphere.