Myanmar’s military rained artillery fire on a camp for displaced people in the northern part of the country, killing 29 people and wounding 56 others, a spokesperson for an ethnic rebel group that controls the area said Tuesday.

The attack late on Monday was the deadliest single assault by the military junta on civilians in six months, fueling further outrage as the armed forces wage a brutal campaign to reclaim rebel-held sections of Myanmar more than two years after a coup.

“I would say this is an act of genocide on our ethnic people,” Naw Bu, a colonel in the Kachin Independence Army, an insurgent group, said by telephone.

The victims were internally displaced people from a camp that housed about 500 near the town of Laiza on the Myanmar-China border, according to Naw Bu. Among the dead, 11 were under 16 years old, including six under age 12. The youngest victim was one-and-a-half years old.

The spokesperson for Myanmar’s military did not answer repeated telephone calls.

Naw Bu said the Kachin Independence Army was weighing the possibility that the shells were shot by drones because those on the ground did not hear the sound of planes overhead.

Photographs and videos from the camp showed bodies strewn in a jungle. A man was seen carrying the mud-soaked body of a young child out of the destruction. Roofs of houses were blown off. On Tuesday morning, people gathered for a mass funeral, in which rows of body bags lined the wall of a hospital.

Since the February 2021 coup, fighting between the army and a large swath of the population who have taken up arms has remained intense. Many of the armed rebels have taken refuge with ethnic armies such as the Kachin Independence Army, one of Myanmar’s most powerful insurgent forces, which has been battling the country’s military for years.

In April, the military killed at least 170 people in a bombing in the central region of Sagaing, in the regime’s deadliest aerial attack since the coup. Last year, the military launched an airstrike that killed at least 80 people at a concert venue in Kachin, in the country’s north.

The country’s generals, under pressure to reclaim parts of the country controlled by rebels, have launched airstrikes against its own people. Last month, the UN high commissioner for human rights said the number of airstrikes had more than doubled in the second year after the coup.

The Assistance Association for Political Prisoners, a rights watchdog, said that 4,143 civilians had been killed by the army since the coup.