The nightclub is cordoned off after it was set on fire in Coatzacoalcos, Mexico, on Aug. 28, 2019. The death toll has reached 26 after a bar was set on fire in eastern Mexico, the state prosecutor general's office said on Wednesday. (Photo: Angel Hernandez/Xinhua)

The death toll from a bar fire attack in eastern Mexico has reached 26, with 11 people injured, the state prosecutor general's office said on Wednesday.

Assailants set fire to the Caballo Blanco Bar in the coastal city of Coatzacoalcos in Veracruz state on Tuesday night, and then closed the emergency exit to trap those inside.

Most of the fatal victims, including 10 women, died from asphyxiation.

Veracruz Governor Cuitlahuac Garcia condemned the attack, saying federal investigators are cooperating with state authorities and vowed that the crime "will not go unpunished."

The motive of the attack was not immediately clear. But initial investigation suggested it was an act of retaliation after the owner refused to let a gang sell drugs in the bar, Garcia said.

Earlier media reports said the fire broke out after attackers rushed into the bar and threw Molotov cocktails.

Veracruz has been riven by violence since mid-2016, as drug trafficking rings using state ports to ship drugs abroad battle each other for local trade.

In April, members of a criminal ring killed 14 people at a family gathering in the oil city of Minatitlan, next to Coatzacoalcos, in a revenge attack against the owner of two bars used by rival drug dealers, according to a police report.