In one of their most gruesome slaughters to date, Islamic State militants stormed the city of Deir al-Zour in eastern Syria over the weekend, reportedly decapitating upwards of 150 people, including women and children, and abducting hundreds more.

“At least 150 people were beheaded yesterday by ISIS in the massacre of Deir al-Zour, including dozens of women and children,” reported the Italian ANSA news service, citing local sources in Syria.

State officials in Damascus place the number of deaths at 300, of whom most were women, children and elderly. Some of the victims were allegedly crucified.

The jihadists carried out a door-to-door massacre of civilians in Ayash and Begayliya, two Deir al-Zour neighborhoods controlled by the Syrian regime, sources reported.

The UK-based Syrian Observatory for Human Rights said that Islamic State soldiers kidnapped at least 400 civilians from families loyal to the regime from the Begayliya area during their attack Saturday, transferring them to the western countryside of Deir al-Zour. The Observatory confirmed that among the dead were also soldiers, paramilitaries and their families.

The attackers first targeted military positions, but on being repelled, moved on to slaughter civilians. “They sent six suicide bombers first and they tried to break into military positions but they failed,” said one Reuters source.

Deir al-Zour province forms a strategic link between Islamic State’s de facto capital in Raqqa and territory controlled by the group in Iraq, and is also considered the Syrian oil hub.

Prime Minister Wael al-Halaqi spread the blame for the attack to “all countries that support and finance the ISIS terrorist horde.”

Military loyal to the government of Bashar al-Assad launched a counter-offensive, backed by air support, and violent fighting continued in the area through Sunday.

Across the Iraqi border, ISIS jihadists launched an assault on an area to the northwest of Ramadi, which had been recaptured by the Iraqi army and its allies last week. ISIS militants reportedly took control of seven army barracks.

Ramadi itself is a pile of rubble. According to a UN report, 4,500 buildings are damaged and 1,500 have been completely destroyed.

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