The official who spoke on condition of anonymity said the gunman had belonged to the security forces "for more than 10 months and was posted to several cities before being transferred to Palmyra".

Besides national, regional and municipal lawmakers, Centrafricans are set to pick their president, with incumbent Faustin-Archange Touadera in pole position out of a seven-strong field after modifying the constitution to allow him to seek a third term.