An earthquake with a magnitude of 5.8 shook Greece’s largest island, Crete, killing one person and injuring 20 others.
The quake also damaged several homes and churches, causing rock slides near the country’s fourth-largest city. Nearby villages were also damaged.
The quake had a preliminary magnitude of at least 5.8.
People fled into the streets in the city of Heraklion.
Authorities declared a state of emergency. However, thousands would spend the night in hotels and tents.
The earthquake’s strength appeared to take seismologists by surprise. “[It] was a bolt out of the blue,” Prof Ethymios Lekkas, who heads the faculty of geology and geoenvironment at the University of Athens, told Greek TV.
“The scientific community thought the phenomenon [of heavy seismic activity] in the region was over. We were all mistaken as the earthquake was totally unforeseen.”
It was too early, Lekkas said, to predict whether a stronger one would follow.
Dr Stephen Hicks, a seismologist at Imperial College London, described the tremor as the most powerful to hit the Mediterranean island since 1959.
The Athens Geodynamic Institute said the quake struck at 9.17am (6.17am GMT), with an epicentre 246km (153 miles) south/south-east of the Greek capital, Athens.
Greece has been facing what has been described as its worst heatwave for more than three decades.
Athens saw temperatures climb as high as 45 degrees Celsius (113 degrees Fahrenheit). Forecasters predict they will reach 40 C later on Wednesday.
Fresh fires broke out late as strong winds and blistering heat continued to complicate the efforts of rescue crews.