Syrian rebels on Thursday seized control of most of Aleppo’s central prison, freeing hundreds of detainees, an NGO said, prompting a denial from state media.

The Syrian Observatory for Human Rights said members of the Islamic Front coalition, dominated by the Ahrar al-Sham brigade and Al-Qaeda affiliate Al-Nusra Front, mounted the assault.

“Ahrar al-Sham and Al-Nusra Front have taken control of 80 percent of Aleppo central prison and freed hundreds of prisoners,” Observatory director Rami Abdel Rahman told AFP.