More than 500 people have died over the past eight days in southern Yemen's main city, Aden, many with breathing difficulties, city officials say, raising fears the coronavirus is spreading out of control, feeding off a civil war that has left the country in ruins.

One gravedigger told The Associated Press he'd never seen such a constant flow of dead — in a city that has seen multiple bouts of bloody street battles during more than five years of war. Condolence messages for deaths in Aden have streamed out on Twitter and other social media for days. Some report multiple deaths within a single...