Isis has claimed responsibility after least 44 people were killed and more than 100 wounded in a twin bombing in a predominantly Kurdish town in the north of Syria.
Syrian state-TV said a truck loaded with explosives blew up on the western edge of the town of Qamishli, near the Turkish border.
Minutes later the attack was followed by a blast from an explosives-packed motorcycle in the same area.
The blasts caused massive damage to the area and rescue teams are working to recover victims from under the rubble.
The town is mainly controlled by Kurds but Syrian government forces are present and control the airport.
Isis claimed responsibility for the attack through its propaganda agency Amaq, which said over 100 had been killed in a truck bombing attack on the headquarters of "Kurdish units".
The bomber drove a cattle van and used live sheep for camouflage, the Hawar news agency reported.
The Britain-based Syrian Observatory for Human Rights said the explosion targeted a center of the local Kurdish police and a nearby government building.
Qamishli resident Suleiman Youssef, a writer, told The Associated Press he heard the first explosion from few miles away. He said the blasts leveled several buildings to the ground and many people were trapped under the rubble.
"Most of the buildings at the scene of the explosion have been heavily damaged because of the strength of the blast," he added.
Isis has carried out a series of bombings in Kurdish areas of Syria in the past. Qamishli has been targeted by the group several times.
The predominantly Kurdish US-backed Syria Democratic Forces have been the main force fighting Isis in northern Syria and have captured wide areas from the extremists.
The attack came as Kurdish forces are conducting an offensive on the Isis-held town of Manbij in northern Syria, further east of Qamishli.
