An Assyrian Orthodox church was attacked Monday in the northeastern Syrian city of Qamishli, resulting in extensive damage to its interior, local sources said.

“Anonymous gunmen stormed the St. Charnel Church for Assyrian Orthodox in the Watwatiyah district of Qamishli in the midnight on Monday, and destroyed its contents,” a spokesman for the Assyrian Monitor for Human Rights told ARA News.

It’s not the first time Qamishli has been subject to a militant attack. Islamic State claimed responsibility for three attacks on the city last December that killed more than a dozen people.

The Assyrian Monitor added the unknown attackers used Molotov cocktails, and that icons and other contents were destroyed.