At least 21 people were killed and more than hundreds others injured in earthquakes that struck a densely populated part of the Albanian coast early on Tuesday, TV Klan reported, quoting the Defence Ministry.
Rescue teams searched through the rubble of collapsed buildings for missing people in the area surrounding the port city of Durres and nearby Thumane, government spokesman Endri Fuga tweeted.
"The powerful earthquake which hit has caused serious consequences and unfortunately we have lost lives," Prime Minister Edi Rama said earlier.
"All structures of the state were put in place from the very first moments after the earthquake ... and are working intensely to save every possible life in Durres and Thumane," Rama tweeted.
Fabio Hasani, a resident of the nearby capital of Tirana, said the tremor triggered panic when it struck at around 4 am (0300 GMT), with many people running into the street and remaining there for about an hour.
"I woke up, confused, feeling my bed moving. Then I realized that everything was moving and shaking, the walls were creaking," Hasani told dpa. "It shook for around a minute."
The European Union and countries in the region offered condolences and assistance to Albania.
"We express our deep condolences to the people and the authorities of the country," EU foreign affairs spokeswoman Maja Kocijancic said on Tuesday in Brussels.
The EU's Emergency Response Coordination Centre has been in "continuous contact" with Albania's civil protection authorities, she added.
Rama said that Germany, Kosovo, Serbia, Italy, Bulgaria and Greece have offered or sent emergency teams to assist.
The 6.4-magnitude earthquake that struck shortly before 4 am was the strongest in three decades, local media reports said.
The epicentre was about 10 kilometres deep and just north of Durres, about 25 kilometres west of Tirana, according to the US Geological Survey (USGS).
A second, 5.5-magnitude earthquake struck the same area just after 7 am.
Another major tremor, of magnitude 5.4, struck south-western Bosnia, near the border with Croatia and its historic city of Dubrovnik at around 10 am.
Overall, the European-Mediterranean Seismological Centre (EMSC) reported 20 tremors with an epicentre under Albania, 16 under the Adriatic and two in Bosnia between midnight and 11 am.
Some damage was reported in southern Montenegro and south-western Bosnia, and tremors were felt across the Adriatic, in Italy, and throughout the Balkans.
The region was also hit in late September, by a magnitude-5.8 tremor, which struck about 60 kilometres north-west of Tirana, injuring dozens.
STRONGEST QUAKE SINCE 1926
Tuesday's quake was the strongest to hit the Durres region since 1926, seismologist Rrapo Ormeni told local television.
The tremors were felt across the Balkans, from Sarajevo in Bosnia to the Serbian city of Novi Sad almost 700 kilometres away, according to reports in local media and on social networks.
The quake was followed by several aftershocks, including one of 5.3 magnitude, the European-Mediterranean Seismological Centre said. Albanian Authorities described it as the strongest earthquake in the last 20-30 years.
The Balkans is an area prone to seismic activity and earthquakes are frequent.
