Tunisia announced it would send its army into its major cities and at the same time arrested 9 people Thursday following Wednesday massacre of 20 tourists who were all shot dead at a museum, which the militant group Islamic State claimed responsibility for and said it was just the first drop of rain that would pour down on the country.

British, Italian, Japanese, Colombian and Spanish visitors along with three Tunisians were amongst the dead. The attack was carried out inside a heavily guarded compound of the parliament in a country that has been largely spared violence in the aftermath of Arab Spring.

Officials would not confirm the claim made by the militant group, but did say they identified the two gunmen killed following the shooting, which had targeted buses carrying tourists visiting on Wednesday at the Bardo museum.

MSC Cruise announced that 12 passengers including French, Belgian and Columbians were amongst the dead, while a couple from Spain was found alive after hiding the entire night inside the museum.

The assault was the most deadly in Tunisia involving foreigners since a suicide bombing in 2002 hit Djerba.

The country is very reliant on tourists from other countries to go from desert treks to beach resorts. The government was close to tackling reforms that are politically sensitive aimed at boosting growth in the economy.

Islamic State is very active in Libya a neighbor of Tunisia. The group praised both attackers in recordings that called them knights of the Islamic State.

Tunisians are one of the biggest contingents of foreign fighters in Libya, Iraq and Syria and the young democracy in the country, which has tightened control on militancy at home, was a clear target.

One of the two dead militants had spent time in Libya and Iraq, but that was not confirmed by authorities. Habib Essid the Prime Minister of Tunisia said that one of the militants was under surveillance but not for anything specific.

Authorities in Tunisia have detained four directly linked with the attack and 5 others who had indirect ties. The father and sister of one of attackers were arrested in Sbiba City.