55 people were left injured by the blast in Syria's northeastern town of Hasakah.
At least 20 people were killed and 55 wounded during a suicide bombing that struck a wedding in the northeastern Syrian city of Hasakah on Monday, Syrian Observatory for Human Rights reported.
"A suicide bomber blew himself up inside a hall in Tall Tawil village during the wedding of a member of the Syrian Democratic Forces, killing at least 22 civilians," Observatory chief Rami Abdel Rahman told AFP.
The casualties included women and children, said local sources, speaking on condition of anonymity due to security concerns.
A witness named Ahmad, who suffered a head wound due to the blast, described the moment the bomber struck.
"As the bride and groom were exchanging their vows I saw a man wearing a thick black jacket pass beside me.
"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."
Syria has been locked in a vicious civil war since early 2011 when the Assad regime cracked down on pro-democracy protests which erupted as part of the Arab Spring uprisings – with unexpected ferocity.