Four people have been killed in the district of Nangade, in Mozambique's northern Cabo Delgado province, local sources said on Friday.
Two victims, one of which is a teacher at a local school, were decapitated by an armed group when driving on a dirt track near the town of Mwangaza to participate in the start of the teaching year.
That same morning, a couple was decapitated when working in their vegetable garden in the same town, the same sources said.
Around 150 people have been killed since October 2017. The groups involved have never made any demands nor announced their intentions, but researchers suggest that violence is linked to networks involved in the trafficking of heroin, ivory, rubies and timber.
The attacks are taking place at a time when major investments are being made by companies in oil and natural gas fields in the region, although the attackers have not broached the area set aside for these enterprises.