The explosion in Idvor, north of Belgrade, occurred at 2:30 a.m. Sunday (0030 GMT Sunday; 8:30 p.m. EDT Saturday) when a man activated the grenade at the entrance to the club. About 150 customers were inside at the time. Serbia's state TV says the man was angry because he and three of his friends were refused entry by the club's security. He and one of his friends were killed in the blast.
Such incidents aren't unusual in Serbia since the wars in the Balkans in the 1990s when many hand grenades and firearms were taken home from warfronts.