The extremist terrorist group, the Islamic State, ISIS, announced Thursday that it is behind Wednesday’s Tunisian museum attack in which 19 people were killed.

Announcing the claim in an audio recorded in Arabic language posted on YouTube by France 24, the group which has been largely operating in Iraq, Syria, and Yemen described the attack as “the first drop of rain”.

“We tell the apostates who sit on the chest of Muslim Tunisia: Wait for the glad tidings of what will harm you, o impure ones, for what you have seen today is the first drop of the rain,” the group announced in the audio recording.

The Tunisian prime minister, Habib Essid, announced in a press statement that the two gunmen killed by the country’s security forces during the siege have been identified to be Tunisians, giving their names as Hatem al-Khashnawi and Yassin al-Abidi.

The prime minister who spoke with journalists at French RTL radio however stated that their affiliation was unconfirmed at the moment.

“We have identified them; it is indeed these two terrorists. Their affiliation is not clear at the moment,” he said.

The prime minister further stated that Yassin al-Abidi had been under surveillance prior to the incident, while a statement from the president’s office disclosed that soldiers would be deployed to streets in major cities to prevent future occurrence of such terror attacks.

Meanwhile, Reuters has reported that Tunisian security have arrested four people who are directly linked to the attack, along with 5 others who have indirect ties.

“We arrested the father and the sister of the terrorist Hatem Al-Khashnawi in their home in Sbiba City,” Reuters reported that a security source revealed.

The attack which occurred at the antiquity-rich Bardo Museum in Tunis Wednesday claimed the lives of Tunisians, Italians, Spaniards, Japanese and Britons.