Nine people were arrested Thursday in connection with a terror attack at the National Bardo Museum in Tunisia, the Washington Post reported. Their identities or alleged role in the deadly assault have not yet been released.

Five gunmen reportedly stormed the renowned museum in Tunis on Wednesday. The attack killed 23 people, mostly foreign tourists. Two of the attackers – identified as Yassine Laabidi and Hatem Khachnaoui – were also among the dead. Laabidi had earlier been flagged by Tunisia’s intelligence services, Tunisian Prime Minister Habib Essid said in an interview with France’s RTL radio Thursday.

It is not yet known if Laabidi and Khachnaoui were linked to a specific terrorist group, but the Islamic State group has claimed responsibility for the attack. The attack came just two days after social media accounts linked to the Islamic State group claimed that a planned attack on Tunisia was imminent