The fighters attacked the village of Kelele overnight, leaving four men and two women dead, administrative official Njiamoja Sabiti told AFP. The victims were either hacked to death or shot, he said.
Kelele, around 12 kilometres (seven miles) from the town of Eringeti, is in Ituri province bordering the conflict-torn North Kivu province.
Sabiti said a search for victims and survivors was still under way, and that the death toll could rise.
A civil society official, Bravo Vukulu, confirmed the death toll.
On Sunday, ADF rebels killed seven people at Kokola, around 45 kilometres north of Beni in a sector of North Kivu where the group is accused of massacring nearly 400 people since November.