An air strike by the Saudi-led coalition fighting opponents of President Abedrabbo Mansour Hadi killed six civilians from the same family by mistake on Wednesday, a provincial official said.
Warplanes targeted the home of a suspected member of the Islamic State group in Huta, the capital of southern Lahj province, but missed and hit an adjacent house, the official told AFP.
The Arab coalition carried out raids on Wednesday on several positions in Huta suspected of being used by jihadists, including an abandoned water bottling plant and an arms depot, another official said.
Coalition air strikes in Yemen dropped significantly after a UN-brokered ceasefire was agreed in April by the government and Iran-backed Houthi rebels who control the capital, paving the way for talks in Kuwait.
While most of the raids have targeted the Houthis, in recent weeks the coalition has also used its fire power to support pro-government forces fighting jihadists.
Al-Qaeda and rival IS have sought to exploit the power vacuum caused by the war between the Houthis and the government to strengthen their presence in the south and southeast.
Pro-Hadi forces supported by the coalition managed last year to drive the Houthis out of Lahj and four other southern provinces.
Huta has since been the scene of frequent clashes between jihadists and government forces struggling to tighten their grip on the city.
Loyalists recently ejected Al-Qaeda from parts of the main southern city of Aden, as well as Huta and Mukalla in the southeastern province of Hadramawt.