Attackers kill 20 tourists and three Tunisians in Tunisian Bardo museum

Update. The death toll of Wednesday's attack at the Bardo Museum in Tunishs has risen. Not 17 but 20 foreign tourists have been killd, as well as three Tunisians. Among the dead were Japanese, Italian, Spanish and British visitors.The attack has been praised by the Islamic State in an audio recording in which it called the attackers  "knights of the Islamic State" armed with machineguns and bombs.
The two gunmen were trained at a jihadist camp in Libya, the Tunisian government said. Interior ministry official Rafik Chelli said the two men had been recruited at mosques in Tunisia and traveled to Libya in September. The two dead militants were identified as Tunisians, Hatem al-Khashnawi and Yassin al-Abidi. Two local newspapers reported Abidi had spent time in Iraq and Libya, but officials did not confirm that. Tunisia's Prime Minister Habib Essid said Abidi had been under surveillance but "not for anything very special". (End of Update).
Two as yet unknown asaillants attacked the National Bardo Museum in central Tunis on Wednesday and killed 17 foreign tourists and two members of the Tunisian intervention force before they themselves were killed, the Tunisian prime minister Habib Essid said after the crisis was over. Twenty four people were wounded. According to the prime minister his government was working to find out the identity of the two attackers.
Tunisia has been more stable than other countries in the region, but it has struggled with violence by armed groups in recent years,including some linked to the Islamic State of Iraq and the Levant (ISIL)group.
Tunisia also has fighters linked to al-Qaeda's North Africa arm who occasionally target Tunisian security forces. Wednesday's assault was the worst attack involving foreigners in Tunisia since an al-Qaeda suicide bombing on a synagogue killed 21 people on the tourist island of Djerba in 2002.
The National Bardo Museum, built within a 15th-century palace, is the largest museum in Tunisia with collections covering two floors, and it houses one of the world's largest collections of Roman mosaics.
The attaque took place after a periode of political uncertainty following the fall of president Ben Ali in 2011 had been followed by  a political solution that seemd to haev brought back some stability in the country.  After the anti-Islamist coalition Nida Tounes won the election in October 2014, its leader Beiji Caïd Essebsi (88) was elected president in December. This was followed by the formation of national unity government led by Nida Tounes byt also comprising members of the islamist Ennahda party, that had been leading the country in 2012 and 2013.
The way this conflict was solved between two camps that had been fighting each other for months, was by many seen as a real example of how to reconcile antagonist political forces with each other. It is not  impossible that it was just that reconciliation that Wednesday's attackers wanted to destroy. 
But, four years after the reign of Ben Ali was finished, the security forces are still battling Islamist militants including Ansar al Sharia, which is listed as a terrorist group by Washington, and Okba Ibn Nafaa, a brigade of al Qaeda-affiliated fighters operating in the Chaambi mountains along the Algerian border. The fight against these militants may have played a role in prompting the museum attack.
Update, Friday: Tunisian authorities said they had arrested four people directly linked to the attack and five others with indirect ties. A security source said two family members of one of the gunmen were among those held. "We arrested the father and the sister of the terrorist Hatem Al-Khashnawi in the their home in Sbiba City," the source told Reuters.
The president's office said the army would be deployed to the streets as part of increased security following the attack. "After a meeting with the armed forces, the president has decided large cities will be secured by the army," it said.