Under a hail of gunfire and grenades, heavily armed militants believed to be linked to Al-Qaeda stormed the intelligence services' jail in a southern Yemen port city Saturday, killing at least 13 people, security officials said. An eyewitness outside the security building in Aden, about 320 kilometers south of the capital, San'a, said the gunmen made off with several freed prisoners. Security officials said the dead included 10 security officers and three women who worked in the building. Nine others were injured, they said. The blatant prison break highlights the challenges Yemen's government faces in battling increasingly brazen Al-Qaeda elements. Saturday's attack began when armed men wearing military uniforms fired on the entrance of the regional intelligence headquarters, then shot their way into its detention facility, where Al-Qaeda suspects are often held, the security officials said. The eyewitness, who works at the building and was outside the premises at the time of the attack, said he saw four gunmen hit the entrance with rocket-propelled and hand grenades before rushing inside under a hail of gunfire. He said a firefight ensured, but the attackers managed to escape with several detainees they had freed from the facility. The eyewitness said he saw at least 10 seriously wounded or dead bodies lying near the building before ambulances took them away. The eyewitness spoke on condition of anonymity for fear of reprisals. He said the attackers had driven up in a car and a minivan, which they parked by a neighboring hotel before attacking the intelligence headquarters. Nearby residents also reported heavy gunfire and plumes of smoke rising from the building, as well as ambulances leaving the area. Hospital officials said at least 15 people had been brought to the local hospital in Aden but did not say if any were dead. No group immediately claimed responsibility. – Agencies for the attack, but the security officials said it had the typical signs of Al-Qaeda and that security forces had arrested about eight people suspected of involvement.