QAMISHLI -- A group of gunmen attacked Monday an Assyrian Orthodox Church in Qamishli city in northeastern Syria, local sources and eyewitnesses reported. "Anonymous gunmen stormed the St. Charnel Church for Assyrian Orthodoxes in the Watwatiyah district of Qamishli in the midnight on Monday, and destroyed its contents," a spokesman for the Assyrian Observatory for Human Rights told ARA News. The militants have reportedly detonated explosives inside the church, which caused a huge damage to the building. "After several explosions were headed inside the church, we saw a huge fire and security forces arrived and extinguished the fire. But the church was completely destroyed, you can see only ashes here," Gabi Gawriya, an eyewitness, told ARA News in Qamishli. The Assyrian Observatory reported that the gunmen had stolen donation boxes from the church before bombing it. Although the perpetrators are not identified yet, Assyrian activists accused ISIS group of being behind the attack.