At least 21 people were killed when the most powerful earthquake to strike Albania in decades shook the capital Tirana and the country’s west and north on Tuesday, tearing down buildings and burying residents under rubble.

Residents, some carrying babies, fled apartment buildings in Tirana and the western port of Durres after the 6.4 magnitude quake struck shortly before 4AM.

The Balkan country was jolted by 250 aftershocks after the main tremor, Defence Minister Olta Xhacka said, two of them of magnitude 5, testing strained nerves.

She told reporters that the quake’s epicentre was in Durres, Albania’s main port and a tourist spot, adding: “Around 600 residents were injured and received treatment.”

In the northern town of Thumane, Marjana Gjoka, 48, was sleeping in her apartment on the fourth floor of a five-storey building when the quake shattered the top of the building.

“The roof collapsed on our head and I don’t know how we escaped. God helped us,” said Gjoka, whose three-year-old niece was among four people in the apartment when the quake struck.

The quake was centred 30 km west of Tirana, the US Geological Survey (USGS) said, and was also felt across the Balkans and in the southern Italian region of Puglia, across the Adriatic Sea from Albania.

Hours later a magnitude 5.4 earthquake rattled Bosnia, with an epicentre 75 km south of the capital Sarajevo, monitors said. There were no reports of injuries.

In Durres, 13 bodies were pulled from collapsed buildings and 45 people were rescued from the wreckage there and in Thumane.

The images of damage from Tuesday’s quake suggested it was stronger than one in 1979 which razed a district of a northern town.

Albania is the poorest country in Europe, with per capita income a quarter of the European Union average, according to the International Monetary Fund.