A Tunisian soldier opened fire on colleagues at a military base in the capital Tunis on Monday, killing an officer and two others and wounding 15 more before being shot dead himself, Tunisian authorities said.

“The armed forces took control of the situation after firing on the soldier,” ministry spokesman Belhassen Oueslati told Agence France-Presse.

It wasn’t immediately clear what motivated the soldier but authorities said the shooting “was not a terrorist attack.” Meanwhile, a nearby school was evacuated.

The shooting took place at the Bouchoucha barracks, near the National Bardo Museum where 22 people – mostly tourists – were killed in a terrorist attack on March 18.

Since overthrowing its secular dictator in in 2011, Tunisia has been battling militant groups with links to ISIS and al-Qaeda, which have carried out attacks on security forces.