The assault represents a marked escalation in fighting with rebel groups that erupted around a disputed Dec. 27 election. The groups attacked towns close to Bangui last month but did not reach the capital as intended.

A Reuters witness in Bangui heard explosions and later saw helicopters circling over the city.

“The attackers who came in large numbers to take Bangui have been vigorously pushed back,” Ngrebada said in a post on Facebook, urging citizens to remain calm.

The gold- and diamond-rich country of 4.7 million has been hit by violence since former president Francois Bozize was ousted by a rebellion in 2013. Thousands have been killed and more than a million forced from their homes. (Reporting by Antoine Rolland Writing by Alessandra Prentice; Editing by Alison Williams and Nick Macfie)