Ayten Bicer felt her 12-year-old daughter slip from her grasp and disappear as the ferry they were travelling on capsized off the coast of northern Cyprus on Sunday, killing eight people.

Her daughter Miray and six-year-old son Memhet Asaf are among 20 people still missing after the vessel sunk while en route to Turkey from the coastal town of Kyrenia, in the self-proclaimed Turkish republic on Cyprus.

She and her husband, Hayri, survived and, like many other families, are waiting for news of their loved ones back in port as rescuers continue to search.

“She was saying, ‘Don’t let go’. And I didn’t let go of my daughter. I swear, I didn’t let her go,” Bicer told reporters through tears.

Bicer said a suitcase fell on top of her, which forced her daughter from her grip. She managed to grab hold of her daughter’s foot, but her shoes were coated in engine oil from the overturned vessel and she slipped through her hands.

“It was slippery everywhere. It was like oil. She slipped out of my hand,” she recalled.

The family was returning to Turkey after a holiday on the Mediterranean island.

“We couldn’t intervene, we lost our children,” Hayri Bicer said. “Two of my three children are gone. We left them. We are leaving them on this island as we go.”

The vessel had been carrying 259 passengers and eight crew members. Nineteen passengers are currently being treated in hospitals in northern Cyprus, local authorities say.

The eight crew members, including the ship’s captain, and one other man were formally arrested on Monday. They will be detained for three days, while warrants have been issued for several other people.

The privately owned ferry left the popular holiday resort of Kyrenia at about 12:30 (09:30 GMT), en route to the town of Tasucu in Turkey.

It had been scheduled to travel to Turkey on Saturday but its journey was delayed due to severe storms hitting the island. The seas were still rough on Sunday.

Some eyewitness accounts say the double-hulled ferry jolted violently before slamming onto the sea surface, with part of its bow bursting open on impact.

Ünal Üstel, prime minister of the Turkish Republic of Northern Cyprus (TRNC), which is only recognised by Turkey, told local media the boat was hit by two waves before it capsized.

While the captain of the vessel was trying to recover from the first wave, a second wave hit and it began taking on water, he said.

The boat has completely sunk and is lying at a depth of 514m (1,686ft), officials say.

Debris remains scattered across the water, including a black wheelie suitcase bobbing on the surface and a sheet of steel that appeared to have broken away from the ferry.

Authorities are attempting to recover the vessel’s black box recorder to establish what happened.

A ship will be arriving from Turkey on Tuesday to help with search efforts, TRNC President Tufan Erhurman said.

Meanwhile, a three-day period of national mourning began on Monday.

The ferry – a high-speed 40m long, 10m wide Filo Jet vessel – sails under the flag of Turkey, according to Marine Traffic.

Filo Denizcilik, the company which operates the capsized passenger boat, said it was “deeply saddened by the tragic accident”.

The TRNC controls the northern third of the island of Cyprus, which has been divided since 1974.