Unidentified gunmen attacked on Monday afternoon the Central Prison compound in the southern port city of Aden, a security source told Yemen Post.
The attack came simultaneously with violent riots by the inmates inside the Al-Monsoura Central Prison, said the source.
The unknown gunmen assaulted the prison's guards at the back gate, compelling the guards to repress the fire with a barrage of bullets. The terrorists then were being forced to run away.
The attack was probably intended to release some militant prisoners, according to the source.
No causalities were recorded so far, another security source told Yemen Post.
Ministry of Interior has announced early this month that it had information that terrorist groups were planning to carry out attacks on the Central Prison with the aim of setting some of their cronies free.
Eyewitnesses told Yemen Post unanimously that heavy security presence were witnessed in and around the Central Prison.
Like other southern provinces, Aden has lately witnessed sharp deterioration of security order with militant groups believed to be linked with al-Qaeda are more frequently seen roaming the streets of the city.
Aden Central Prison in al-Mansoura area was the scene of riots and prisoners escape in December last year.