A French woman identified as Madame Dupeu died Saturday as the result of the severe injuries she sustained March 18 when gunmen affiliated with the Islamic State group shot up the Bardo National Museum in the Tunisian capital city of Tunis, French President Francois Hollande’s office said in a statement. Dupeu was the fourth French national to die because of the attack, whose death toll is now 22, according to the Associated Press.

The statement did not provide details about either Dupeu’s identity or the wounds that led to her death. The Tunisia museum attack’s victims included citizens of France, Italy, Japan, Spain and the U.K., as reported by Reuters.

Hollande will be in Tunis Sunday to participate in a march to commemorate those who died in the attack. The event is expected to draw a crowd of thousands. The Bardo National Museum will reopen the same day.

On the day of the attack, masked gunmen, identified as Tunisian nationals Jabir al-Khashnawi and Yassin al-Abidi, entered the museum and opened fire on tourists with automatic weapons. Police later killed both men. The Islamic State group claimed responsibility for the massacre in a subsequent audio message.

Tunisian authorities are searching for a third suspect who is believed to have played a role in the attack. “Two were executed, but one is still on the run. But he won’t get very far,” Tunisia’s President Beji Caid Essebesi said in a March 22 interview, according to the U.S.-funded Voice of America.

Police have arrested 23 people who they described as participants in an al Qaeda-affiliated terrorist cell that contributed to the museum attack, France 24 reported Thursday. One man, a Tunisian national named Maher Ben Mouldi Kaidi, purportedly provided the automatic weapons that were used in the assault. Lokmane Abou Sakhr, an Algerian national, was identified as one of the attack’s organizers.

Despite the Islamic State group’s claim, officials have yet to confirm which terrorist group, if any, was truly responsible for the raid. A police officer tasked with surveillance at the museum was imprisoned and five other security personnel were fired after the attack, AP reported.