Flash floods on the outskirts of Athens have converted roads into raging torrents of mud and debris, killing at least five people and inundating homes and businesses.
The fire department said another four people were reported missing by their families and crews were searching for them.
All five fatalities - two women and three men - occurred in the Mandra area in separate incidents.
The bodies of a woman and a man were initially found in their flooded homes while later another two men and one woman were found dead, two in the yards of local businesses and one near a road.
The flooding came after severe weather overnight, with a storm hitting the area with driving rain.
Firefighters received at least 340 calls for help to pump water from flooded buildings and rescue people trapped by the rising waters.
Crews also rescued passengers from a bus stranded by the floodwaters.
Local authorities shut schools in the areas of Mandra, Nea Peramos and Megara, while access was cut on parts of the Athens-Corinth motorway leading through the area.
The fire department appealed to the public to avoid heading to the area unless absolutely necessary in an effort to reduce traffic.
The deaths came a day after Greek authorities declared a state of emergency on the small Aegean Sea island of Symi after torrential rainfall flooded homes and shops, swept vehicles into the sea and cut power after the local power station was flooded.
More bad weather has been forecast for various areas of Greece in coming days.