Yemen's Houthi militants fired Sunday mortars and rockets at Saudi Arabia's southern city of Najran, prompting the Saudi military to bombard Houthi sites northern Yemen, Sky News Arabeya reported. The Shiite rebels struck May 5 a girls' school and a hospital in Najran, which is only three km (two miles) from Yemen's border, prompting authorities to close down all schools in the area. Spokesperson for the Saudi-led Arab Coalition, Brigadier Ahmed Assiri said the Houthi aggression seek to thwart any humanitarian relief or pan-Yemeni political factions' talks.