The clashes erupted early on Wednesday when gunmen from the Mai Mai militia attacked a military center in the town of Beni, 220 miles (350 kilometers) north of Goma, said army spokesman Col. Olivier Hamuli.
Twenty four gunmen, five army recruits, two soldiers and a lieutenant colonel were among the victims, he said.
Resident Jean Kambale said heavy gunfire lasted until afternoon.
The Mai Mai militia groups are indigenous to the region and insist that they are Congo’s true patriots. Since the 1990s, the Mai Mai fighters have forged and broken alliances with a variety of domestic and foreign government and guerilla groups in a country that has experienced interminable cycles of violence for nearly 15 years.
Several armed groups, including the March 23 movement (M23) rebels, also are active in the eastern Congo and fighting for control of the country’s vast mineral resources, such as gold, the main tin ore cassiterite, and coltan (columbite-tantalite), which is used to make many electronic devices, including cell phones.
Since early May 2012, nearly three million people have fled their homes in the eastern Congo. About 2.5 million have resettled in Congo, but more than 460,000 have crossed into neighboring Rwanda and Uganda.
Congo has faced numerous problems over the past few decades, such as grinding poverty, crumbling infrastructure, and a war in the east of the country that has dragged since 1998 and left over 5.5 million people dead.