BEIRUT — Hundreds of Kurds fleeing Islamic State-held villages in northern Syria amid a wave of mass abductions have come under fire, with several killed or wounded, opposition activists and a Kurdish official said Saturday. In eastern Syria, meanwhile, air strikes on a village controlled by the extremist group have killed at least 30 people, opposition activists said. In the northern province of Aleppo, hundreds of Kurds fled as the Syrian Democratic Forces, a U.S.-backed and predominantly Kurdish militia, clashed with Islamic State fighters inside Manbij, a key stronghold of the extremist group.