It's thought the 6 men and three women, all in their 50s, were freed late last night and sent back to a church in the city of Hassakeh.
Bashir Saedi, a senior official in the Assyrian Democratic Organisation, said the fate of the other captives is unclear.
The group were taken as the extremists retreated from Tal Tamr in the face of a counter offensive by Kurdish forces last Monday.
A monitoring organisation claims to have evidence the IS fighters referred to the captives as 'crusaders'.
It has been suggested a ransom could have been paid for the 19 Christians but this has not been confirmed.