Tunis: Tunisian Prime Minister Habib Al Sid fired six police commanders on Monday, including the head of tourist security, after a terrorist attack on the national museum last week in which 20 tourists were killed.

The premier’s office spokesman, Mofdi Mssedi said the six also included an intelligence brigade chief, the Tunis district police chief, the traffic police commander, a Bardo security chief and a commander for the capital’s Sidi Bachir district.

“Prime Minister Habib Al Sid visited the Bardo Museum yesterday...and took note of several security failures there,” Mssedi said.

Gunmen killed 20 foreign tourists, including Japanese, Polish, Italian and Spanish visitors, last Wednesday as they got off buses at the Bardo Museum, inside the parliament compound that is normally heavily guarded.

It was the worst attack in more than a decade in Tunisia, testing the North African country’s young democracy four years after the revolt that overthrew autocrat Zine Al Abidine Bin Ali.

Two gunmen were shot dead at the scene and authorities have so far arrested more than 20 people, 10 of whom officials believe were directly involved in the attack. Some had recently returned from fighting for Islamist militant groups in Syria, Iraq and Libya.

Daesh terrorists fighting in Iraq and Syria claimed that their supporters carried out the attack although a local Al Qaida affiliated group known as Okba Ibn Nafaa has also published details and comments on the assault.

Tunisia has been largely spared the violent aftermath of the Arab Spring uprisings of 2011, with secular and Islamist parties overcoming their divisions to compromise, approve a new constitution and hold free elections.

Hardline Islamist groups also emerged after the revolt against Bin Ali swept away his one-party rule. Since then security forces have been caught up in a growing battle with extremists, some of whom are returning from training and fighting overseas.

Authorities say the two gunmen killed in the Bardo attack had trained in militant camps in Libya. More than 3,000 Tunisians left to fight in Syria and Iraq, and hundreds have returned.