( CNN ) The terrorists who attacked the Bardo Museum in Tunis , Tunisia , last week were wearing suicide vests but failed to detonate them before being gunned down by police , Tunisia 's President told CNN . `` They had them , but they did n't work , because the police turned up and they were shot down and they did n't have the time to get these vests to work . Because had they done so , we would have had major catastrophe , '' President Beji Caid Essebsi told CNN 's Christiane Amanpour . A third museum attacker remains at large , Essebsi said . Previously two suspects had been identified -- Yassine Labidi and Saber Khachnaou -- though it was n't immediately clear if they were the pair killed at the museum by Tunisian security forces . Essebsi told Amanpour 15 arrests had been made since Wednesday 's attack , in which 23 people were killed . Most of the victims were foreigners and 19 were tourists who 'd been on two cruise ships that docked in Tunis . Essebsi said he believed the attackers were members of ISIS who had been trained in Libya . This echoed comments made by Tunisia 's Security Minister Rafik Chelly on Friday , who said two attackers had been given weapons training at Libyan camps and had been activated from sleeper cells . In an audio message posted online Thursday , ISIS claimed responsibility for the attack . The message said the group had targeted `` crusaders and apostates '' with `` automatic weapons and hand grenades '' in bloodshed that was `` just the start . '' CNN can not independently verify the legitimacy of the audio statement . An uncle of suspect Yassine Labidi , Abeld Malik Labidi , told CNN on Friday that no one he knew had seen any signs of extremism in his 26-year-old nephew . He said Yassine Labidi was one of the two gunmen killed at the museum . `` It 's true that Yassine carried out this terrorist attack , he was killed ; his head , his body , we do n't have it back , '' he said . But , he said , he believed Yassine and other young Tunisians like him were also victims of terrorism -- of the recruiters who paid them money , organized the logistics and took them to places like Syria and Libya to train as fighters . Laura Smith-Spark and Claudia Morales contributed to this report .
The Bardo Museum attackers wore suicide vests , CNN 's President tells Tunisia . Police shot them before they could detonate the vests , Beji Caid Essebsi says . Essebsi says 15 people have been arrested over the deadly attack .