Italian rescue teams were trying on Wednesday to save six family members, including twin toddlers, trapped under rubble when their house collapsed after Albania's worst earthquake in decades.

The death toll from Tuesday's quake rose to 30 as rescue workers dug through the remains of the four-story house in the Adriatic port city of Durres.

Nine members of the Lala family were initially trapped but a boy of 17 was pulled out alive on Tuesday and the bodies of a 79-year-old woman and an eight-year-old girl have been recovered.

The rescue workers, watched by relatives and the twins' father, believe two girls aged 18 months, two boys of six and seven, a 16-year-old girl and a disabled man of 52 are still under the rubble.

In addition to the 30 dead across the country, the Defense Ministry said 650 people had been injured and 20 were missing.

If the death toll continues to rise, the earthquake could be more deadly than one in 1979 when 40 people were killed.

The quake, centered 30 kilometers (19 miles) west of the capital Tirana, was felt across the Balkans and in the southern Italian region of Puglia, on the other side of the Adriatic Sea from Albania.

A 5.3 magnitude quake also struck just off Albania's coast on Wednesday afternoon 38 kilometers from Tirana, causing cracks to a high-rise apartment building in a main street in the capital.

Residents fled and police cordoned off the area.

In the town of Thumane, close to the center of Tuesday's 6.4 magnitude quake, rescuers used drones and dogs in search for survivors.

Temperatures in Albania were expected to remain well above 10 degrees Celsius (50°F) in the coming days but rain forecast for Thursday could hamper the rescue efforts.

Located along the Adriatic and Ionian Seas between Greece and Montenegro, Albania is prone to seismic activity. A quake measuring 6.0 also jolted the Greek island of Crete on Wednesday though no damage or injuries were reported.

Albania was shaken by at least 250 aftershocks - three of them magnitude 5 - from Tuesday to Wednesday. Hundreds of people spent the night sleeping in tents pitched by the emergency services.

Italy, France, Romania, Turkey, Greece, Croatia, Montenegro, Kosovo and Serbia have sent 200 specialized troops, tools and teams of tracker dogs to help the relief effort.

The government declared Wednesday a day of mourning and Prime Minister Edi Rama said the authorities would rehouse people who had lost their homes in hotels during the winter.

"I believe we shall put them in new houses in 2020, in better housing than they had," Rama said in a televised comment.