ISIS reportedly stormed the city of Deir Ezzor in northern Syria over the weekend. At least 400 families of pro-regime fighters were captured by ISIS and transported to the countryside, according to The Syrian Observatory for Human Rights and CNN. In a similar report, Syria's official news agency, SANA, stated that ISIS had, "committed a massacre in al-Bagaliyeh," which is just north of the city. Approximately 300 were murdered. On Monday, Syria's Foreign Ministry delivered letters to the UN requesting assistance.

The above numbers include soldiers, women, children and the elderly, all of whom are Sunnis. In one attack, several suicide bombers were positioned at the Furat Cham Palace hotel, which is on the banks of the Euphrates river.

ISIS has conducted 30 suicide attacks within the past 48 hours. The tactic of having the first military person to reach the army's fortification detonate has proven to be a successful one in gaining territory.

Aamaq ISIS news agency said that 167 regime fighters had been killed, with many more wounded. The regime forces were reportedly backed by Russian airstrikes.

The Observatory's head, Rami Abdurrahman, said, "There is genuine fear for their lives, there is a fear that the group might execute them as it has done before in other areas."

The attacks over the weekend began with a suicide car bomb blast on Saturday. ISIS claimed responsibility for the attack in a statement, also declaring that jihadists had carried out several suicide bombings against regime forces, and that it now had control of Deir Ezzor and Al-Baghaliyeh.

Much of Deir Ezzor was already controlled by ISIS, but Syria's eastern desert holds a plethora of oil and gas fields, which is a significant source of income for ISIS. These fields have been bombed multiple times by a US-led coalition and British warplanes when they began bombing targets in December. ISIS has lost large territories to various forces over the past few months. One area, in particular, includes territory in northern Syria near Raqqa, where American-backed Kurds gained ground.

The Syrian conflict began primarily as a peaceful uprising against President Bashar al-Assad in March 2011 but quickly grew into a full-blown civil war in which over 250,000 people have been killed. The UN estimates that the conflict has also caused about 4.3 million others to become refugees.

The city has been under siege since last March, causing food, water and medicine shortages. It has also been without electricity since that time, with the conditions being comparable to a concentration camp environment.