Rescue teams are searching through the debris of eight collapsed buildings in search of survivors after a powerful earthquake struck Turkey’s Aegean coast and the north of the Greek island of Samos, killing at least 27 people.

More than 800 others were injured in the quake which struck on Friday afternoon, toppling buildings in Izmir, Turkey’s third largest city, and triggering a small tsunami in the district of Seferihisar and on Samos.

The quake was followed by hundreds of aftershocks.

Early on Saturday, onlookers cheered as rescuers lifted teenager Inci Okan out of the rubble of a devastated eight-floor apartment block.

Friends and relatives waited outside the building for news of loved ones still trapped inside, including employees of a dentist’s surgery that was located on the ground floor.

Two other women, aged 53 and 35, were rescued from another collapsed two-storey building.

At least 24 people were killed in Izmir, including an elderly woman who drowned, according to Turkey’s Disaster and Emergency Management Presidency, or AFAD.

Two teenagers were killed on Samos after being struck by a collapsing wall.

At least 19 people were injured on the island, with two, including a 14-year-old, being airlifted to Athens and seven taken to hospital on Samos, health authorities said.

The small tsunami that hit the Turkish coast also affected Samos, with seawater flooding streets in the main harbour town of Vathi. Authorities warned people to stay away from the coast and from potentially damaged buildings.

The earthquake, which the Istanbul-based Kandilli Institute said had a magnitude of 6.9, was centred in the Aegean, north-east of Samos. AFAD said it measured 6.6 and hit at a depth of some 10 miles (16km).

It was felt across the eastern Greek islands and as far away as Athens and in Bulgaria.

In Turkey it shook the regions of Aegean and Marmara, including Istanbul. Istanbul’s governor said there were no reports of damage in the city, Turkey’s largest.

Turkey is crossed by fault lines and is prone to earthquakes. In 1999, two powerful quakes killed some 87,000 people in north-western Turkey. Earthquakes are frequent in Greece too.

Authorities warned residents in Izmir not to return to damaged buildings, saying they could collapse in strong aftershocks. Many people spent the night out in the streets, too frightened to return to their homes, even if they sustained no damage, the DHA news agency reported.

More than 3,000 rescue personnel were sent to Izmir, as well as relief supplies. The Turkish Red Crescent set up kitchens.

In a show of solidarity rare in recent months of tense bilateral relations, Greek and Turkish government officials issued mutual messages of solidarity, while the presidents of Greece and Turkey held a telephone conversation.

Relations between Turkey and Greece have been particularly tense, with warships from both facing off in the eastern Mediterranean in a dispute over maritime boundaries and energy exploration rights.

The ongoing tension has led to fears of open conflict between the two neighbours and Nato allies.