A tourist is helped to a vehicle after an attack by gunmen on Tunisia's national museum in Tunis, March 18, 2015. [Photo/Agencies]

Tunisia is particularly vulnerable to such attacks because its economy has struggled since 2011.

At a news conference Thursday, Prime Minister Habib Essid announced new security measures around the country, including a crackdown on websites seen as promoting terrorism.

The deaths of so many foreigners will damage Tunisia's tourism industry, which draws thousands of foreigners to its Mediterranean beaches, desert oases and ancient Roman ruins. The industry had just started to recover after years of decline.

Two cruise ships that had 17 passengers among the dead quickly left the port of Tunis early Thursday, citing safety concerns, and the vessels' operators suspended visits to the country.

Culture Minister Latifa Lakhdar gave a news conference at the museum, where blood still stained the floor amid the Roman-era mosaics.

"They are targeting knowledge. They are targeting science. They are targeting reason. They are targeting history. They are targeting memory, because all these things mean nothing in their eyes," she told reporters.

In the afternoon, authorities opened the gates of the museum for a rally in defiance of the bloodshed. About 500 people - some carrying flowers for the victims - held a moment of silence before singing Tunisia's national anthem. Participants included black-robed lawyers, families with children, and teenagers swathed in the red-and-white Tunisian flag.

A funeral was held for Aymen Morjen - an elite member of Tunisia's security force who was killed at the museum. Interior Minister Mohamed Najem Gharsalli and House Speaker Mohamed Ennaceur attended the service.

It was among the museum's Roman-era mosaics that the militants dressed in military uniforms and armed with grenades and assault rifles took hostages and began shooting the foreigners.