Three bombs exploded in Qamishli in northeast Syria on Monday, killing five people and wounding 26 in the city, which is largely-controlled by Kurdish fighters, security forces said, reports Reuters.
Two cars and a rigged motorcycle exploded near a cafe and a church, a statement from the region's security forces said. The wounded included four security force members, it said, describing the blasts as a "terrorist operation".
With the Kurdish YPG militia at its forefront, the Syrian Democratic Forces (SDF) defeated Daesh across much of north and east Syria with US help.
A series of bomb attacks have struck towns and villages in northern Syria in the past year, including in the SDF region.
Kurdish leaders say Daesh sleeper cells still pose a threat and warn that a Turkish offensive at the border would allow a jihadist resurgence.
Ankara launched its incursion last month into northeast Syria to target the YPG, after President Donald Trump's decision to move US troops out of the way. Turkey deems the YPG a threat linked to a decades-long Kurdish insurgency at home.