The armed insurgents swooped on the group of gamblers at remote Gendamari in Aagia police station and randomly fired on them at around 9 PM, police said.
The injured were taken to Goalpara Civil Hospital by the locals, who alleged that the police came late at the site of the firing.
Meanwhile, senior police officers have rushed there from the district headquarters town of Goalpara, the source said.
They attack security forces and civilians, trigger blasts and kidnap people to extort money.