The bomber blew himself up late Monday in the village of Tall Tawil in Hasakeh province where a Kurdish party official was getting married.
Rows of seats in the wedding hall were still covered in blood on Tuesday morning, according to a photographer at the scene.
“As the bride and groom were exchanging their vows I saw a man wearing a thick black jacket pass beside me,” a witness named Ahmad said.
“I thought he looked strange and a few seconds later there was an enormous explosion.
“People had fallen on the ground and I saw bodies torn to bits.”
About 100 people were wounded, according to the medical source in Hasakeh city who gave the updated toll.
The Syrian Observatory for Human Rights, a British-based monitoring group, gave a slightly lower toll of 31 people killed.
The Islamic State (IS) group said in a statement that one of its fighters had fired on a “large gathering” of Kurdish fighters near Hasakeh city before blowing himself up.
The claim, which did not mention a wedding, said 40 people had been killed.
Both the groom and bride were safe, but the groom’s father and brother were killed in the attack, a relative told media.
“The groom’s wounds are light, and he and his new wife are staying at a relative’s home. He doesn’t want to see anyone,” he said.
“They are really shaken up by this.”
The groom, Zaradesht Mustafa Fatimi, hails from a prominent family deeply involved in the autonomous administration run by Kurdish factions in Syria’s north.
According to an official from the autonomous administration, Fatimi works for a local Kurdish party.
The Observatory said he is also a member of the Syrian Democratic Forces, an Arab-Kurdish coalition battling IS in northern Syria.
Hasakeh city is almost entirely held by Kurdish forces but Syria’s regime still holds some districts. The city has often been targeted by IS militants.
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