Hundreds of prisoners escaped the Ngaraba jail on Monday in Bangui, the capital of the Central African Republic.
"There is no one in the prison," a source told Reuters. Another told the Associated Press that more than 500 prisoners had left.
Up to 42 people have been killed in the capital in recent days, the worst violence this year.
The murder of a Muslim man sparked reprisal attacks on a Christian neighborhood over the weekend. UN peacekeepers were forced to fire warning shots to disperse thousands of protesters who were calling for an increased role for the nation's army.
The majority Christian country has been plagued by violence since March 2013, when largely Muslim Seleka rebels ousted the president. The violence has killed thousands and displaced nearly a million people.
The Seleka rebels relinquished power in January 2014. A transitional government, led by interim President Catherine Samba-Panza, has been given the task of organizing elections for this October.
Samba-Panza, who was in New York at the UN General Assembly on Monday, left early to deal with the trouble at home.
Earlier this year, UN troops in CAR were accused of rape and of having sexually abused children in the country.
jr/cmk (Reuters, AP)