Sanaa , Yemen ( CNN ) -- More than 40 al Qaeda militants infiltrated Yemen 's port city of Aden seeking to free imprisoned fighters , the defense ministry said Saturday . The ministry said the militants entered through neighboring al-Thale province , and that the country is on high security alert . `` The same group of militants already attacked a government prison in al-Thale province seeking to release members of the terror network arrested in a military operation earlier this week , '' a senior Defense Ministry official told CNN on condition of anonymity because he is not authorized to talk to media . Dozens reported killed by al Qaeda land mines in Yemen . The militants were heavily armed and attacked the governmental complex with rocket-propelled grenades and a barrage of bullets . `` After failing to free prisoners in al-Thale , they headed towards Aden . Our forces are ready and will ensure the safety for Yemen 's business capital , '' the official said . Hundreds of reinforcement troops were deployed to Aden since Thursday . Prison breakouts are not new for Yemen . Last week , 24 al Qaeda militants escaped a highly secured prison in the southwestern province of al-Hodieda , security officials in the province confirmed to CNN . Top Yemen commander killed ; al Qaeda claims responsibility . Meanwhile , the Interior Ministry said Saturday that its forces seized control of all government buildings in the town of Azzan , Shabwa . The town was the last al Qaeda stronghold in Yemen . Al Qaeda took over numerous towns in southern Yemen last year , benefiting from the political instability in the country . The crisis resulted in a transfer-of-power deal forcing longtime President Ali Abdullah Saleh to step down from power . Newly elected President Abdu Rabu Mansour Hadi intensified the fight against al Qaeda and vowed to continue the assault on militant hideouts until the group is defeated . Over the past month , more than a dozen militants were arrested throughout Yemen , including prime suspects behind deadly suicide attacks against government forces . White House : Military is fighting terrorism in Somalia and Yemen .
More than 40 militants enter port city of Aden , threatening to free imprisoned fighters . `` Our forces are ready and will ensure ... safety , '' a Defense Ministry official says . Hundreds of reinforcement troops are brought in to prepare for a possible break .