A Yemeni policeman was killed and four wounded when security forces repulsed gunmen trying to storm the central prison in Sanaa Thursday, security officials told AFP.
Residents said an explosion and heavy gunfire rang out near the jail, in the capital's north, where officials say around 5,000 prisoners are held, before security reinforcements were dispatched to the area.
Another security officer told AFP "an attempt to storm the central prison has been foiled and the assailants have fled," saying there was no information on who they were or what their objective was.
In October, security forces foiled an attempt by some 300 Al-Qaeda inmates to escape after they mutinied in another Sanaa prison.
A number of guards and inmates were wounded but none were killed.
Nasser al-Wuhayshi, chief of Al-Qaeda in the Arabian Peninsula -- seen by the United States as the network's deadliest franchise -- vowed in August to free imprisoned members of his network.
Wuhayshi himself escaped from the same Sanaa prison with 22 other members of AQAP in February 2006 and was named as the group's leader a year later.
The AQAP detainees escaped through a 44-metre (145-foot) tunnel they dug between their cell and a nearby mosque.
AQAP has taken advantage of the weakening of the central government in Sanaa since a popular uprising that toppled president Ali Abdullah Saleh in 2011.