Over 148 people have reportedly died in a serial suicide bombing conducted in northwestern Syria on Monday, considered as the deadliest attacks to date.

The responsibility for the attacks at the coastal heartland of President Bashar Assad’s regime has been claimed by the Islamic State group. In an online statement, the ISIS declared that they targeted the members of the Alawite sect of Shiite Islam, where Assad belongs to. In the statement, the group also specified that they were planning “more devastating and bitter attacks” as they aimed at taking revenge against the Syrian regime and Russian air strikes launched against the extremists.

Seven serial blasts targeted hospitals, bus stations and other public sites across the seaside cities of Tartus and Jableh. These areas have always remained protected from Syria’s five-year war until now, and these attacks have left no safe territory in Syria anymore. According to a Yahoo News report, around 100 people were killed in Jableh and another 48 died in Tartus. SANA news agency in Syria reported four explosions that included a suicide bombing at the emergency entrance of the Jableh national hospital. CBS News reported many deaths, including that of a nurse at the hospital named Huda al-Houshi.

The dead ones included children as well, according to the Syrian Observatory for Human Rights monitor. Observatory Head Rami Abdel Rahman said they were, undoubtedly, “the deadliest attacks” on the two cities since the five-year war commenced.

The Observatory head said that two suicide bombers in a car detonated explosive belts that destroyed the bus station in Tartus completely. Within 15 minutes of the bus station bombing, four more explosions rocked Syria’s Jableh’s north. The hospital was attacked by one suicide bomber, according to reports.

The triggered responses from various state figures. UN Chief Ban Ki-moon condemned the terrorist attacks while France said it was “heinous.” On the other hand, US State Secretary John Kerry called Russian counterpart Sergei Lavrov and requested him to ask the Syrian regime to delay the Aleppo and Daraya attacks for now.