At least 70 people are dead and 30 others have been injured after an attack in Haiti's breadbasket Artibonite region, a human rights group says.
The reported toll from the Collective Defending Human Rights group far exceeded figures provided by authorities earlier.
Police initially reported 16 dead and 10 injured, while a preliminary report from civil protection authorities suggested 17 had died and 19 were wounded.
A spokesperson for the UN Secretary-General told reporters during a press briefing that he strongly condemned the gang attack where the death toll estimates ranged from 10 to 80 people.
The spokesperson said the violence underscored the gravity of the security situation in the country and urged a thorough investigation.
The Collective Defending Human Rights group said the "massacre" had forced nearly 6000 people to flee their homes.
"The lack of a security response and the abandonment of Artibonite to armed groups demonstrate a complete abdication of responsibility by the authorities," the group said in a statement.
Armed members of the Gran Grif gang attacked the Jean-Denis area at approximately 3am on Sunday, local civil protection authorities said.
The attack followed United Nations reports that more than 2000 people were recently displaced by armed raids in nearby Verrettes, prompting residents in Petite-Riviere to flee their homes.
The Artibonite department, a key agricultural area, has seen some of Haiti's worst violence as gang conflict spreads beyond the capital, Port-au-Prince.
In March, the US offered a reward of up to $US3 million for information on the financial activities of the Gran Grif and Viv Ansanm groups.
Washington has designated both, which represent coalitions of hundreds of gangs, as terrorist organisations.
Haitian security forces, supported by a UN-backed international mission and a US private military company, have intensified operations against gangs that control most of the capital. However, authorities have yet to arrest a major gang leader.
More than a million people have been displaced by the conflict with gangs, which has exacerbated food insecurity, and close to 20,000 have been reported killed in Haiti since 2021.
The death toll has climbed every year.