The mass break-out on Tuesday occurred as a hearing was taking place in their prison in Gemena to try to reduce the backlog of defendants awaiting trial.
Lawyers said the inmates began throwing stones as the court sat through the second of 60 cases scheduled that day.
Mutinies are frequent in Congolese prisons where conditions are harsh.
The BBC’s Thomas Hubert in the capital, Kinshasa, says after decades of neglect and successive wars, the Congolese justice system is barely functioning, with many courthouses in ruins and devoid of basic equipment.
“It looked like a crowd walking out of a church or a stadium,” Francis Wombali, a lawyer assisting a defendant at the hearing that was taking place inside the prison, told the BBC.
Prosecutor Felicien Kibeka said the prisoners became unruly in the overcrowded room where only two policemen were present to maintain order.
He said he barely had time to jump into a car and save his life before the prisoners broke through the prison gates.
Our reporter says security forces in Equateur province are dealing with the aftermath of a rebellion in the area earlier this year and are unlikely to be on the hunt for the others.
Mr Kibeka says he is the only prosecutor covering the town of Gemena and the surrounding villages in Equateur province.
The magistrates appointed to help him have never arrived and as a result the backlog of cases in the area keeps increasing.
As a consequence the prison is overcrowded with inmates in pre-trial detention, Mr Kibeka said.
For his part, Mr Wombali said the prisoners escaped because they were not fed and had no means of survival while in detention.
DR Congo’s justice minister has described prisons as “death houses” and called on the international community to help improve conditions.
The UN peacekeeping mission in DR Congo has recently opened a special office to tackle the problem.
Around 2,000 new magistrates were recruited last March, half of whom were due to take up their posts this year, but their deployment has been delayed in many areas.
Source: BBC