A storm over northern Greece lasted only 10 minutes late on Wednesday night but it killed six people and injured at least 60 others, with one person still missing.
A state of emergency was declared in the region because of the toppling of trees and power pylons, leading to power cut and blocking of roads.
The devastation left thousands without water, power, and phone services.
The defense ministry deployed soldiers with power generators to the affected areas.
The confirmed victims, two of them children, were all tourists, from Romania, the Czech Republic and Russia. A 60-year-old fisherman was still missing a day later, authorities said.
The storm which slammed the three-fingered Halkidiki (Chalkidiki) peninsula east of Thessaloniki overturned cars, motorcycles, threw tables around and damaged buildings.
A Czech couple was killed when the wind-tossed their camper at Sozopol. The thrashed camper ended on its roof, its content is strewn around the beach.
Further east, in Nea Plagia, a Romanian woman and her son were killed when a part of a restaurant canopy they sought shelter under collapsed.
The wind picked the child up and violently threw him around, the thestival.gr portal quoted witnesses as saying.
In Nea Potidea, to the south-east, a Russian tourist and his two-year-old son were killed by an uprooted tree.
The storm moved through shockingly fast, people said.
“I turned as I felt raindrops stinging my back. The wind whipped them so powerfully that I thought it was pebbles hitting me,” a man from the area told the Skai TV channel.
Greek meteorologists said the storm was a phenomenon which occurs only near the sea. They had been warning that a storm was likely during the string of very hot days preceding it.
“We knew it was coming and warnings were issued, but could not forecast where,” the national disaster protection chief meteorologist, told radio Thema104.6.
The heat of up to 40 degrees warmed the sea for days, creating updrafts. When that hot air collided with cooler air, it effectively created a tornado storm.
Greece, which was hit by a financial crisis in 2010 and has only emerged from a third bailout in August, recently suffered a series of disasters.
A brush fire a year ago killed 100 people and destroyed hundreds of homes. Several flash floods also claimed lives and damaged homes inflicted massive damage.