The death toll from an attack carried out by the Islamic State (ISIS) on a Syrian military bus in eastern Syria on Thursday evening has risen to 33, according to the Syrian Observatory for Human Rights on Saturday. The organization launched its most severe attack since the beginning of the current year, targeting a military bus in the desert of the al-Mayadeen region in the eastern countryside of Deir ez-Zor. They ambushed the bus and targeted it with light and medium weapons. The director of the observatory, Rami Abdul Rahman, told Agence France-Presse (AFP), "The death toll from the attack on the military bus has risen to 33 soldiers." After gaining control over vast areas of Syria and Iraq in 2014, the extremist organization faced successive defeats in both countries, eventually losing all its controlled territories by 2019. Since then, it has lost four of its leaders, but its hidden elements are still capable of launching limited attacks against various targets, especially against government forces.