A strong earthquake of magnitude 6.2 struck central Greece.
The European Mediterranean Seismological Centre said on Wednesday the quake hit at a depth of 10 kilometres below the surface at about 12.15pm local time.
Its epicentre was about 22 kilometres north-west of the city of Larissa, in Thessaly region.
There were no immediate reports of injuries or major damage.
People rushed out of homes and office buildings as the quake struck.
"I have never experienced anything like this before, I immediately left the house," one resident said.
There were at least three aftershocks following the main tremor – including one at magnitude 4.0 – and authorities said there could be more.
Costas Agorastos, a governor in Thessaly, said schools in the region were advised to close.
A fire service official in Athens said there were no reports of damages or injuries.
Greek seismologist Vassilis Karathanasis told state television the tremor was felt across Greece.
People in Albania, North Macedonia, Kosovo and Montenegro also reported feeling tremors.
Turkish Foreign Minister Mevlut Cavusoglu said Turkey would provide Greece with "all the support we can, if needed".
The US Geological Survey and the Global Seismic Monitor Geofon put the quake’s preliminary magnitude at 6.3, while the seismological institute of the Aristotle University of Thessaloniki put the magnitude at 6.0.
It is common for magnitudes to vary between seismological institutes in the early hours after an earthquake.
Greece lies in a highly seismically active region, but the vast majority of earthquakes cause no damage or injuries.
Last October, an earthquake that struck the eastern Greek Aegean island of Samos and the nearby Turkish coast killed two people on Samos and at least 75 people in Turkey.
