Two of the gunmen who carried out the attack on a museum in Tunisia's capital city of Tunis on Wednesday had received weapons training across the border in Libya, a senior Tunisian official reportedly said.

“They left the country illegally last December for Libya and they were able to train with weapons there,” Rafik Chelly, Tunisia’s secretary of state for security, reportedly said on Friday. However, it is not yet clear which group the two men, identified as Yassine Laabidi and Hatem Khachnaoui, had trained with. Earlier, the Islamic State group had claimed responsibility for the attack in an audio statement released on Thursday, reportedly calling it an attack on “crusaders and apostates.”

Wednesday's attack at the Bardo Museum killed at least 21 people, including 17 foreign tourists. However, since there is no information yet on what type of contacts Laabidi and Khachnaoui had with ISIS, and because none of the group’s statements are direct messages from the gunmen, ISIS' involvement in the attack has not yet been confirmed.

“I think (ISIS) is probably taking credit for something it may not have played a role in,” Geoff Porter, a security analyst for North Africa, told the Associated Press.

Among those killed in the attack are at least three Italians, three Japanese and two French nationals, two Spaniards, two Colombians and one citizen each from Britain, Poland and Belgium. The two identified attackers were also killed. However, reports of the casualty numbers as well as the name of one of the two attackers identified so far have been inconsistent.