At least 22 people were killed by a suicide bomber in an attack targeting a party in the northeastern Syrian province of Hasakeh, the Syrian Observatory for Human Rights and medics said.
A witness named described the minute the bomber struck.
“As the bride and groom were exchanging their vows I saw a man wearing a thick black jacket pass beside me,” he said.
“I thought he appeared odd and several seconds after there was an enormous explosion.
“People had fallen on the ground and I saw bodies torn to bits.”
The Observatory and local Kurdish officials said the bridegroom was among the dead, but one of his relatives told AFP that both bride and groom were safe and well.
The AFP correspondent saw many hurt folks, some with bloodied bandages on their heads.
A source in the Asayesh security forces in the self-administered Kurdish territories also said a suicide bomber had blown himself up in the wedding hall several kilometres (miles) north of Hasakeh.
IS said in a statement that among its fighters had fired on a “large gathering” of Kurdish fighters near Hasakeh city before blowing himself up. The claim, which didn’t mention a wedding, said 40 people were killed.
The virtually entirely Kurdish-held city has often been targeted by jihadists of the Islamic State group.