NEW : Islamic State kill troops , mostly in southern Yemen . The goal of the anti-government gunmen was to protect the anti-government demonstrators , who have repeatedly come under fire from security forces during the past two months . Fiercest clashes in Taiz since March began , witnesses say . A government official says Yemeni President Ali Abdullah Saleh is ` ` severely hurt '' Opposition leaders express cautious support for the vice president .
NEW : Islamic State kill troops , mostly in southern Yemen . Fiercest clashes in Taiz since March began , witnesses say . A government official says Yemeni President Ali Abdullah Saleh is ` ` severely hurt '' Opposition leaders express cautious support for the vice president .