On Sunday, a "terrorist group" killed 12 people, including two VDP members, at Yargatenga, a village near the eastern border with Togo and Ghana, local sources said.
"This is the third time that Yargatenga has been targeted in a month," a local official said, saying the town's commissioner had been killed in an ambush on February 1.
The attack in Dembo was carried out by "around 100 armed men who surged into the village in pickups and on motorcycles, opening fire before taking on the VDP," an official with the volunteer force told AFP.
"We lost seven members in the fighting, which lasted more than three hours. Several attackers were also killed but their bodies were taken away" by the assailants, he said.
He added that a petrol shortage meant VDP units could not pursue the attackers, though a military force had arrived from Nouna, around 15 kilometers away, on Friday morning.
"Residents have been packing their bags since the weekend," one local in the area told AFP, saying that "terrorists" had arrived in Dembo several times since the beginning of the year "but until now they hadn't killed anyone."
The attacks brought the death toll from armed insurgents to around 60 for last week alone, up from around 50 the week before.
One of the world's poorest nations, Burkina Faso has been rocked by a jihadist insurgency that spilled over from neighboring Mali in 2015.
Thousands have been killed, more than two million people have fled their homes and around 40 percent of the country lies outside the government's control.
Anger within the military at the mounting toll fueled two coups last year.