(Reuters) -- Tens of thousands of Tunisians marched through the capital Tunis in a show of solidarity against Islamist militants Sunday, hours after the government said its forces had killed nine members of a group suspected of carrying out this month’s deadly attack on the Bardo National Museum.

The March 18 attack in Tunis killed 21 foreign tourists and a policeman, shaking a country that has been praised as a peaceful democratic model since leading the first of the Arab Spring uprisings in 2011.

A red-and-white sea of Tunisian crescent-and-star flags filled a major boulevard in Tunis where several world leaders, including French President Francois Hollande, planned to rally under the slogan “Le Monde est Bardo” (The World is Bardo).

“We have shown we are a democratic people, Tunisians are moderate, and there is no room for terrorists here,” said one of the demonstrators, Kamel Saad. “Today everyone is with us.”

Thousands of police and soldiers were positioned around the capital.

One of the most secular countries in the Arab world, Tunisia has mostly avoided violence in the four years since the toppling of autocrat Zine El-Abidine Ben Ali. In contrast with Libya, Syria and Yemen, which all have plunged into war and chaos, it has adopted a new constitution and held free elections.

But the Bardo massacre was one of the worst attacks in the country’s history. Colombian, French, Japanese, Polish and Spanish visitors were among those killed in the attack, which the government says was aimed at destroying Tunisia’s vital tourism industry.

‘Strong Response’

“Tunisia wanted France with them, and France is on the side of Tunisia, the origin of the Arab Spring, and now a victim of a hateful act,” Hollande said in France after voting in local elections before flying to Tunis. Italy’s Prime Minister Matteo Renzi was also due to take part in the demonstration, along with leaders from Algeria, Belgium, Libya, Palestine and Poland.

Tunisia’s Prime Minister Habib Essid earlier told reporters a raid in the southern Gafsa region had killed nine militants from the local group Okba Ibn Nafaa, including Algerian Lokman Abu Sakhr, suspected of orchestrating the museum attack.

“We have killed most of the leaders of Okba Ibn Nafaa who were behind many recent attacks,” Essid said. “This is a clear and strong response to terrorism after the Bardo attack.”

The Islamic State group has claimed responsibility for the attack, although the Tunisian government has pointed the finger at Okba Ibn Nafaa, which has a base in the Chaambi mountains bordering Algeria.

The group was previously more allied with al Qaeda, but has made vague statements on its position toward the Islamic State group, the al Qaeda splinter organization that now controls large parts of Iraq and Syria.

The Tunis attack underscored how Islamist militant loyalties are blurring as they seek a new North African front, especially in Libya, where political chaos and factional fighting has allowed the Islamic State group to gain an outpost.

The two Bardo gunmen were trained over the border in Libya at camps operated by Tunisian militants, officials say. Both were killed by security forces.

(Reporting by Tarek Amara and Mohamed Argoubi; Writing by Patrick Markey; Editing by Mark Trevelyan)