TUNIS: The Islamic State group issued a statement Thursday claiming responsibility for the deadly attack on Tunisia’s national museum that killed 23 people, mostly tourists.

The statement described Wednesday’s attack in Tunisia as a “blessed invasion of one of the dens of infidels and vice in Muslim Tunisia,” and appeared on a forum that carries messages from the group.

The statement said there were two attackers and they weren’t killed until they ran out of ammunition and it promised further attacks.

“Wait for the glad tidings of what will harm you, impure ones, for what you have seen today is the first drop of the rain,” the statement, which was also announced by US-based SITE Group.

Tunisian security forces arrested nine people Thursday, authorities said.

Five of those arrested were directly connected to Wednesday’s attack by two gunmen who were later slain by police, the president’s office said in statement Thursday. The other four suspects were arrested in central Tunisia and were part of a cell supporting those involved, it said.

Prime Minister Habib Essid told France’s RTL radio that Tunisia was working with other countries to learn more about the slain attackers, identified as Yassine Laabidi and Hatem Khachnaoui. He said Laabidi had been flagged to intelligence, although not for “anything special.”

Razor wire ringed the museum Thursday and security forces guarded major thoroughfares in Tunis, the capital.

Two or more gunmen attacked the museum wielding assault rifles and began gunning down tourists in front of a row of about 10 buses. The attackers then charged inside to take hostages before being killed in a firefight with security forces.

A Spanish man and a pregnant Spanish woman who survived hid in the museum all night in fear and were retrieved safely Thursday morning by security forces. Spain’s Foreign Minister said police searched all night for the pair, Juan Carlos Sanchez and Cristina Rubio.