A monitoring group says at least 400 civilians have been kidnapped by Islamic State militants during an attack Saturday on the eastern Syrian city of Deir al-Zour.
The British-based Syrian Observatory for Human Rights says women, children and family members of pro-government fighters were among those captured after IS forces seized the suburb of al-Baghaliyah. The group says at least 135 people were killed in the fighting, many of them Syrian soldiers.
But the state-run SANA news agency says at least 300 people were killed by IS forces during the attack on Deir al-Zour.
The reports could not be independently verified.
Islamic State fighters have previously carried out mass executions of civilians in Iraq and Syria, including the slaughter of 200 soldiers after it seized the Tabqa airbase in Raqqa province in 2014, as well as hundreds of members of the Sheitat tribe in Deir al-Zour that same year.