At least 15 people were killed and 16 others injured in a suicide attack claimed by the Islamic State during a wedding party in Iraq's holy city of Karbala, media reports on Monday.The statement released by the IS-affiliated Amaq news agency said four suicide attackers targeted a Shia gathering late Sunday.One bomber opened gun fire and threw grenades on the wedding party in Ayn-Tamur town of the city.There were five suicide bombers wearing explosive vests who also opened gunfire but security forces shot four of them dead before they could detonate their bombs, Iraqi authorities said.The attacker who targeted the wedding sprayed the crowd with automatic gunfire and threw hand grenades before detonating his suicide vest, officials said.Town authorities have intensified security measures as reinforcement troops arrived from Karbala city, located 110 km from the Iraqi capital of Baghdad.