While deputies debated an anti-terror law in the Assembly of Peoples Representatives (ARP), armed men disguised as soldiers opened fire at the museum next door taking its visitors hostage. The Bardo Museum was the centerpiece of Tunisias ancient heritage and an important tourism attraction.
The tourism industry was already brought to its knees by instability following the 2011 overthrow of dictator Zine al-Abidine Ben Ali. This will dash any hopes of a recovery and have wider repercussions on the economy.
Tunisia has struggled with low-level violence since 2013, when two opposition politicians were assassinated, but managed to confine it to the margins.
The Bardo attack is not the first to target the tourism industry, but it is the first to be successful since the 2002 synagogue bombing, which killed 19.
It steps up the intensity of the threat and raises wider questions over the threat of regional instability in North Africa. The ability of Tunisian security forces to prevent violence in Libya and the Sahel from sweeping through Tunisia is also under question.
The two most active extremist groups in Tunisia are Ansar al-Sharia, strong in deprived urban areas, and the Okba bin Nafaa Brigades, who are fighting a guerilla war with security forces in mountains near the Algerian border.
Escalating violence in Libya is the most severe threat.
There have been several incidents near the border, resulting in increased security. Discoveries of arms by the security forces probably represent the tip of the arms-smuggling iceberg, and the border is thought to be highly porous.
The Libyan Ansar al-Sharia has links to its Tunisian counterpart, while supporters of Islamic State are both expansionist and favour maximum violence.
The anti-terrorism law is more vital than ever, as is the security forces ability to prevent and respond to attacks.
President Beji Caid Essebsi has declared war, but now he must fight it well.