An Oddar Meanchey province man was killed and 18 people were injured Tuesday when an unknown attacker lobbed a grenade into a group of dancers who were celebrating an infant’s three-month birthday in Anlong Veng district’s Thlat commune. Ol Run, the commune police chief, said four of those injured during the attack, which occurred at 10pm in Tuol Kruos village, were in serious condition. “We assume this case was an intentional attack, but there are no clues to identify the attacker,” he said.