"The National Guard has tightened its control over the prison and immediately started tracking down the fugitives in order to arrest them as soon as possible," the ministry said in a statement published by the official news agency early Monday.
Two guards were also injured, it said. The identities of the escaped prisoners were not given.
After the escape, which the ministry said took place at 2100 GMT Sunday, it asked people to report any information that might help in arresting the fugitives.
According to a military official speaking on condition of anonymity, two of the prisoners had been sentenced to death, while the other two were awaiting trial for membership of a terrorist organization.
The same person said their vehicle had been found northeast of Nouakchott.
The death penalty has not been enforced in Mauritania since 1987.
There have been no jihadists attacks in Mauritania since 2011, but the country shares a border with Mali, where a jihadists insurgency that began in 2012 has spread to other Sahel countries.
Jihadi Jailbreak in Mauritania
Four jihadist prisoners escaped Sunday night in Mauritania's capital Nouakchott after an exchange of gunfire at its central prison in which two national guards were killed, the Interior Ministry said.
NOAKCHOTT —