The 14-year-old student died after being hit by a bullet. A further seven people were treated in hospital, an AFP correspondent said.
Protestor Robert Njangala accused police of firing bullets in the area where the teenager was killed, after attempts to disperse the crowd with tear gas failed.
Education minister Ladislas Muganza said protesters who attempted to carry the student’s body to the town hall were blocked by a police cordon.
Protestors in the poor neighbourhood of Panzi ransacked local offices and a police station before setting them on fire.
Locals are protesting against chronic instability, including a spate of armed robberies, in Bukavu, the regional capital of South Kivu province which lies on the border with Rwanda.
The east of the country has been prey to attacks by rival armed groups for more than 20 years.
Local authorities were not available for comment when contacted by AFP.
Meanwhile 34 prisoners — including 27 convicted rapists — escaped from a prison in Mwenga, some 130 kilometres (80 miles) from Bukavu, on Sunday.
It was the latest in a series of violent incidents at prisons in the troubled country.
The prisoners, some serving sentences for murder and robbery, fled in the pouring rain after cutting through the iron bars.
Local authorities said three of the prisoners had since been found.
In June 900 prisoners in the neighbouring province of North Kivu broke free and more than 4,000 fled from a jail in the capital Kinshasa in May.