( CNN ) More than 500 Houthi rebels have been killed since the start of Saudi-led military operations against Yemeni Shia fighters , a Saudi Defense Ministry official said Saturday , according to the state-run Saudi Press Agency . A Saudi general said Saturday the nine-nation coalition has undertaken 1,200 airstrikes since they began on March 26 . Gen. Ahmed Asiri added that the raids aim to keep the rebels from moving toward southern Yemen , according to the SPA . Clashes took place Friday near the Saudi-Yemeni border , in the Najran region . Saudi forces responded to mortar rounds fired by Houthis on a Saudi border site . Three Saudi military officers were killed and two others were wounded in the shelling , a defense official said , according to SPA . A Saudi source also confirmed to CNN 's Nic Robertson that three Saudi soldiers were killed in the shelling . The Yemeni Health Ministry on Saturday said 385 civilians have been killed and 342 others have been wounded . The World Health Organization has put higher figure on both tolls -- 648 killed and 2,191 wounded -- but includes militant casualties in the totals . Yemen has been descending into chaos in the weeks since Houthi rebels -- minority Shiites who have long complained of being marginalized in the majority Sunni country -- forced Yemeni President Abdu Rabu Mansour Hadi from power in January . And even before the crisis escalated with the Saudi airstrikes , most of the 25 million people in Yemen required humanitarian assistance to meet their most basic needs , the United Nations said Friday . CNN 's Pierre Meilhan and Mohammed Tawfeeq contributed to this report .
Saudi general says more than 1,200 airstrikes since campaign began March 26 . The United States has been bombing ISIS targets in Iraq and Syria for nearly a year.