The attack late on Saturday left the soldier's wife, in-laws and two of his children dead before he turned his weapon on other civilians, Ituri province army spokesman Lieutenant Jules Ngongo said.
The soldier was not identified.
The soldier arrived home from his post at another village in the province to find family and community members gathered in mourning for his son, who died on Thursday of natural causes, said Baraka Muguwa Oscar, the local village chief.
"This soldier did not like the fact that his son… was buried without his approval and in his absence," Oscar said.
Elements of the country's army were dispatched to apprehend the soldier, a member of the Armed Forces of the Democratic Republic of Congo, or FARDC, who fled the scene after the attack.
"No matter what the case, the time or the circumstances, you can't take a person's life. This is an act of indiscipline that will be dealt with by the courts," Ngongo said.
Unrest in eastern DR Congo has been simmering for decades as more than 120 groups fight for power, land and valuable mineral resources while others try to defend their communities.
Earlier this week, the United Nations warned of a surge in violence in the country's northeast.
