A deal to evacuate four besieged Syrian towns began on Wednesday with an exchange of prisoners between rebels and government forces, local sources and state media said.
Thousands of people, both civilians and fighters, are expected to begin leaving government-held Fuaa and Kafraya and opposition-controlled Madaya and Zabadani on Wednesday.
The evacuations of the four besieged towns come under an agreement brokered by rebel supporter Qatar and government ally Iran last month.
The opposition released 12 prisoners, nine of whom appeared to be suffering injuries. They arrived in government-held Aleppo city along with eight bodies.
Syrian state news agency Sana said the exchange of prisoners marked the start of the "implementation of the first phase of the agreement".
Fuaa and Kafraya are government-held Shiite-majority villages in the otherwise rebel-controlled province of Idlib.
Madaya and Zabadani are opposition enclaves surrounded by regime forces in Damascus province.
More than 320,000 people have been killed in Syria since the conflict began in March 2011 with anti-government protests.