At least four people were killed by a projectile fired by the Houthi rebels that hit a market in Yemen's oil-rich province of Marib, a government official said.The local government official told Xinhua news agency said that "the projectile fired by the Houthis landed on a popular marked in Al Jubah district in Marib's southern part, leaving four people killed", reports Xinhua news agency.He confirmed that the attack caused damage to the public properties and left nearly six other people injured, including children.Meanwhile, Yemen's Ministry of Defence reported that dozens of the Houthi rebel group were killed and injured in ongoing fighting with the government forces and airstrikes carried out by the Saudi Arabia-led coalition in Marib.The Iran-backed Houthi militia launched in February a major offensive on Marib in an attempt to seize control of the oil-rich province, the last northern stronghold of the Saudi-backed Yemeni government.Yemen has been mired in civil war since September 2014 when the Houthi militia forced the internationally recognized government of President Abd-Rabbu Mansour Hadi out of the capital Sanaa.