At least six suspected al-Qaeda members were killed in a drone strike in central Yemen, local tribal leaders said on Tuesday, following a US warning of a possible major militant attack in the region. The suspected militants died in the fourth American drone attack on Yemen in the past two  weeks, just as President Abed Rabbo Mansour Hadi returned from visits to the US and Saudi Arabia. Tribal sources told Arab Today that five missiles struck a vehicle travelling in Maarib Province, killing all of its occupants, including a local al-Qaeda leader. Last week drone attacks were launched on al-Qaeda suspects in Abyan, Shabwa and Hadramout, killing at least 14 people among them Saudi nationals. Drone strikes on suspected al-Qaeda targets in Yemen are usually carried out by US forces, although Washington does not comment publicly on the practice. The warning issued by Washington on Friday prompted the closure of several Western embassies in Yemen and several US missions across the Middle East and Africa. The New York Times reported on Monday that the closure of the US embassies was prompted by intercepted communication between al Qaeda leader Ayman al-Zawahri and Nasser al-Wuhaishi, head of Yemen-based al-Qaeda in the Arabian Peninsula (AQAP).