At least 70 people have been killed and 30 injured during an attack in Haiti’s breadbasket Artibonite region, significantly more than official estimates, a human rights group has said.

Police initially reported 16 dead and 10 injured, while a preliminary report from civil protection authorities suggested 17 had died and 19 were wounded.

The Collective Defending Human Rights group, which reported the higher death toll, said the “massacre” on Sunday had forced nearly 6,000 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.

A spokesperson for the UN secretary general told reporters on Monday that he strongly condemned the gang attack. They said the violence underscored the gravity of the security situation in the country and urged a thorough investigation.

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 UN reports that more than 2,000 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 $3m 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.