The World Health Organization said Tuesday that a suicide bomber who targeted a hospital in a Syrian coastal city killed 43 people. The latest number raised the death toll from an unprecedented wave of attacks on government strongholds Monday to 154.

The casualties from Monday's explosion at the Jableh National Hospital in the city of Jableh were mostly patients and visiting family members. Three doctors and nurses were also among the dead, WHO said, according to the Associated Press. WHO said the hospital was badly damaged and no longer operational. Several patients at the hospital were victims from at least three other blasts that hit Jableh on Monday.

The bombings, claimed by the Islamic State group, were carried out in Jableh and the city of Tartus — both cities are government strongholds that had not previously been affected by the violence of Syria's five-year civil war.

Syrian government officials said Monday's blasts had killed at least 80 people, while the Britain-based Syrian Observatory for Human Rights put the death toll at 154.