A boy walks next to the tents at a makeshift camp at a soccer stadium in Durres, western Albania, on Wednesday, after the strongest earthquake in decades claimed at least 28 lives, with victims trapped in the debris of toppled buildings. Photo: AFP

Albania was in national mourning on Wednesday as emergency workers continued to pull bodies from the ruins of buildings gutted by a violent earthquake, with nearly 30 found dead and hundreds injured.

Tirana declared a state of emergency in the areas hardest hit by Tuesday's 6.4-­magnitude earthquake: the coastal city of Durres and the town of Thumane, where victims were trapped by toppled buildings. 

With the help of dogs and more than 200 experts flown in from across Europe, rescuers worked through the night to locate survivors.

Early Wednesday in Thumane, emergency workers backed by Greek teams retrieved the body of a young man, an AFP reporter at the scene reported. 

They were also attempting to free a young woman who they believe is still alive after the 24-hour ordeal. 

By Wednesday morning, the death toll was up to 28 while 45 people had been rescued, the defense ministry said in a statement. Some 650 people have also been treated for injuries, mostly minor, according to the health ministry.

The powerful quake, which struck just before 4 am (03:00 GMT) on Tuesday, was the strongest to jolt Albania in decades, according to authorities.

"The priority is to save people's lives," said Prime Minister Edi Rama, who declared Wednesday a national day of mourning and announced a 30-day state of emergency for Durres and Thumane.

Festivities planned for Albania's Independence Day celebration on Thursday and Friday have been canceled. 

Thousands of people spent the night in tents or on the grass of the soccer stadium in Durres, where some 27 buildings were badly damaged.

Many were afraid to return home as more than 300 aftershocks were felt in Albania and the wider region following Tuesday's quake.

In neighboring Greece, a strong 6.1-magnitude underwater earthquake shook the island of Crete on Wednesday morning.

Earthquakes are common in the Balkans due to the movements of two large tectonic plates - the African and Eurasian - and the smaller Adriatic micro-plate.