( CNN ) -- Islamist rebels dressed in government military uniforms approached the gate of a high security prison in Mogadishu on Sunday , set off a car bomb and fired their way into the building , eyewitness Farah Mohammed told CNN . They were Al-Shabaab fighters , and security guards at the prison `` foiled the attack '' and killed seven of the rebels , Somalia 's Information Minister H.E . Mustafa Duhulow said in a statement . `` The attackers exchanged heavy gunfire with prison guards after detonating a car bomb at the main gate , '' Mohamed said . `` A plume of dark smoke could be seen rising from the attacked complex . '' During the assault on the National Intelligence and Security Agency prison three security guards and two civilians were also killed , 15 others were injured , Security Ministry spokesman Mohamed Yusuf told CNN . The attackers tried to free their fellow Al-Shaabab members held at the prison , who were sentenced to death by a Somali military court tribunal , said police Officer Abdifarah Ali . `` We were behind today 's raid on NISA prison in Mogadishu , '' Al-Shabaab spokesman Sheikh Abdiaziz Abu Musab said on pro-militant radio station Al-Andalus . `` Our Mujahideen forces stormed the complex and then sprayed the prison guards with bullets and bombs , '' he said . The government praised the security forces , saying it shows that Somalia has improved security . `` These terrorists groups are against the security improvements we are currently experiencing here in Mogadishu , '' Information Minister H.E . Mustafa Duhulow said in a statement . `` We say to them that these foiled attacks strengthen our forces and prove their bravery to the people of Somalia , '' he said . The NISA prison is underground and is close to the Somali presidential palace in Mogadishu . Hundreds of inmates , mostly Al-Shabaab members , are being held there . Al-Shabaab is an al Qaeda-linked militant group seeking to turn Somalia into a fundamentalist Islamic state , according to the Council on Foreign Relations . The group claimed responsibility for the deadly attack at a Kenyan mall last year and is believed to be responsible for attacks in Somalia that have killed international aid workers , journalists , civilian leaders and African Union peacekeepers . CNN 's Nana Karikari-apau , and Kay Guerrero contributed to this story .
Al-Shabaab rebels try to storm a prison in Mogadishu . Twelve die , including seven Al-Shabaab fighters , in `` foiled attack , '' security forces say . The attackers wore government military uniforms . The prison houses mostly Al-Shabaab members on death row .