"The Kangwayi prison in Beni was attacked at 3:30 pm (1330 GMT) by assailants whose identity is not yet known," Julien Paluku, governor of North Kivu province, told reporters.
"In the exchange of fire between security forces and the attackers, authorities have (counted) 11 dead including eight members of the security forces," Paluku said, adding: "For the moment, out of 966 prisoners, there are only 30 left in the prison."
Paluku said the Beni area and the neighbouring town of Butembo had been put under curfew from 6:30 pm. "Only police officers and soldiers should be out from this time," he said.
The government blames the killings on a rebel group, the Allied Democratic Forces (ADF), which appears to be dominated by Ugandan Muslims.
According to AFP report, the attack came a day after the ADF attacked a police station and a prosecutor's office in the capital Kinshasa, killing a police officer and seriously injuring four others after a series of similar attacks over the past three weeks.
The attack also comes after two jailbreaks occurred last month in Congo. On May19th, dozens of prisoners escaped from a dilapidated prison in Kasangulu, about 40 km west of Kinshasa.