(CNN) At least 23 people have been killed, several more are missing and hundreds have been injured after an earthquake struck Albania on Tuesday.

The quake, which had a preliminary rating of 6.4 magnitude, hit the European nation at an approximate depth of 20 kilometers (12 miles) early Tuesday local time, according to the United States Geological Survey. It is the strongest to hit Albania in 40 years.

The epicenter was in the port city of Durres, about 36 kilometers (22 miles) from the capital Tirana. Social media videos from the area show several buildings have collapsed.

Albanian Prime Minister Edi Rama's office revised the death toll upwards several times on Tuesday. At least four victims died in Durres, spokesman Endri Fuga told CNN. Another two died in Thumane, one person died after jumping from a building in panic in Kurbin, and one victim died while driving on a badly damaged road in Lezhe, the spokesperson added.

Around 45 people were rescued from the rubble, Fuga told CNN, and more than 650 people have received medical attention throughout the day. He added that 30 people are being treated in hospitals.

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