Riyadh, August 16 The Saudi-led coalition bombing rebels in Yemen launched an investigation today following international condemnation of an air strike that Doctors Without Borders said killed 11 people at a hospital it supports. More than 19 people were also wounded in the raid that hit the hospital in Abs, in the rebel-held northern province of Hajja, the Paris-based aid agency said, adding that one of its staffers was among the dead. The hospital strike was the latest in a series of reported coalition raids hitting civilian facilities -- including at a school on Saturday that killed 10 children. The coalition launched the bombing campaign in March last year after the Shiite Huthi rebels and their allies seized control of large parts of the Arabian Peninsula nation. It stepped up air strikes earlier this month after peace talks between the rebels and President Abedrabbo Mansour Hadi’s internationally backed government were suspended. Doctors Without Borders, widely known by its French acronym MSF, said the attack was the fourth on one of its facilities in less than a year. “Once again, a fully functional hospital full of patients and MSF national and international staff members, was bombed in a war that has shown no respect for medical facilities or patients,” Teresa Sancristoval, of MSF’s emergency unit in Yemen, said. MSF said that the GPS coordinates of the hospital “were repeatedly shared with all parties to the conflict, including the Saudi-led coalition, and its location was well-known.” Key Saudi ally Washington raised concerns about the reports, with State Department spokeswoman Elizabeth Trudeau saying: “Strikes on humanitarian facilities, including hospitals, are particularly concerning.” UN Secretary General Ban Ki-moon went further, condemning the reported strike and saying he was “deeply disturbed” by the intensification of air raids in Yemen. “Hospitals and medical personnel are explicitly protected under international humanitarian law and any attack directed against them, or against any civilian persons or infrastructure, is a serious violation of international humanitarian law,” Ban said in a statement.