2010 Baghdad church siege
On 31 October 2010, six suicide bombers of the Islamic State of Iraq (ISI) militant group stormed into the Sayidat al-Nejat Cathedral (a Syriac Catholic church in Baghdad) during Sunday evening Mass, taking the congregants hostage. The ISI was a militant group which aimed to overthrow the Iraqi federal government and establish an Islamic state in Iraq.
Source: Wikipedia — 2010 Baghdad church siege (CC BY-SA 4.0)