At least 29 people, most of them rebel fighters, have been killed in a bombing near Syria's border with Turkey, activists say.
The attack reportedly occurred during a change of guard at the rebel-controlled Atmeh crossing, in Idlib province.
It was not immediately clear whether the blast was caused by a suicide bomber or a remote-controlled device.
A news agency linked to so-called Islamic State (IS) said a suicide car bombing had targeted a rebel convoy.
But an opposition activist network, the Local Co-ordination Committees, reported that a suitcase filled with explosives had been planted at the scene.
In mid-August, 32 rebels were killed in a suicide attack claimed by IS at the Atmeh crossing, which they use to travel from Idlib, via Turkey, to battle the jihadist group in other parts of north-eastern Syria.