ATHENS, Greece — Specialized disaster response crews were combing the area west of Athens Monday for two men missing from last week’s flash floods that killed at least 20 people, while the government announced relief measures for those whose homes or businesses were damaged.

The search operation was concentrating on the Mandra area west of the Greek capital, the hardest hit by Wednesday’s disaster, which was among the worst to have hit the wider Athens area in decades.

The flash floods turned roads into raging torrents of mud and debris that flung cars against buildings, inundated homes and businesses and cut a section of a major highway. Those who died drowned in their homes or were swept away by the floodwater.

Nearly 1,000 buildings were damaged, most of them private houses, as well as businesses, storage areas and public buildings.

Government spokesman Dimitris Tzanakopoulos announced emergency aid for those affected, including a tax-free benefit of 5,000 euros per damaged household and 8,000 euros per damaged business.