The Cn army said it was pursuing the militants and would retaliate.
He said the militants kidnapped several others, who are now missing.
The Allied Democratic Forces (ADF), a Ugandan armed group based in eastern Congo with ties to Islamic State, has been blamed for the killings.
Allied Democratic Forces militants are said to have executed more than 40 men, women and children in five villages since Thursday.
“We are very concerned by credible reports that Rwanda has supported the M23,” the top U.S. diplomat told a press conference in Kinshasa.
The M23 militia began as a renegade force of army mutineers in 2012, committing atrocities and war crimes.
Currently there are the Cooperative for Development of the Congo, the Forces Démocratique pour la libération de Rwanda, and several others.
The ADF is a Ugandan militia that moved to eastern Congo in the 1990s and has killed more than 1,300 people between January 2021 and January 2022.
The assailants, believed to be rebels from the Allied Democratic Forces (ADF), have targeted at least five villages.
The ADF originates in Uganda, but operates from bases in north-eastern Congo to launch attacks back into Uganda.
