At least seven people including a baby and an elderly couple have died following flash flooding caused by torrential rain on the Greek island of Evia.
Many people had to be airlifted to safety after roads were flooded, and the fire department has received hundreds of calls to pump water from houses and vehicles.
One person is still missing and dozens of others remain trapped in their homes and cars.
"At night, at around 4 am, we heard this noise of the water coming down," said Maria, 85, who lives in the village of Politika, where a river burst through its banks and forced many residents to climb to the rooftops of their homes.
She continued: "And then the river, the water, everything started to come into the house. We had to stand up on whatever we could in order not to drown."
Rainfall began on the island, which is northeast of Athens, on Saturday night accompanied by lightning and was much heavier than expected.
Nikos Hardalis, Greece's deputy minister of civil protection, said there had been 350 mm of rain in 24 hours — substantially higher than the 63 mm that was forecast. He said the damage caused by the storm was huge in certain areas of central Evia.
Prime Minister Kyriakos Mitsotakis is expected to visit the region on Monday.
Transport was widely disrupted. Firefighters said they came upon hundreds of dead sparrows after trees were hit by lightning.
Some locals criticised the authorities for not implementing the 112 emergency evacuation system to send a message to all mobile phone users urging them to leave their homes.
But Hardalis said: "If we had done this we would have had hundreds of deaths.
"The 112 emergency messaging system was in place, but when you have a phenomenon like this, you do not ask for any kind of evacuation. It may have cost hundreds of human lives."
Extreme weather is not uncommon in Greece, where 24 people were killed when flash floods hit the town of Mandra west of Athens in November 2017.