At least eight people have died and more than a dozen others are still missing after a passenger boat capsized off northern Cyprus, the head of the Turkish administration there has said.

Ünal Üstel, prime minister of the self-proclaimed Turkish republic on Cyprus, said the ferry had been carrying 259 passengers and eight crew members when it began taking on water after departing the coastal town of Kyrenia.

The ship’s captain and seven crew members have been detained as part of an investigation into “how this tragedy occurred”, Üstel wrote on social media.

A search and rescue operation to find the passengers still unaccounted for is under way, which Turkish authorities have joined.

The privately owned ferry left the popular holiday resort of Kyrenia at about 12:30 local time (09:30 GMT).

Üstel said the boat had been scheduled to travel to Turkey on Saturday, but had been delayed due to poor weather conditions.

He told Turkish media outlet TRT that 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 told the outlet.

Helicopters and coastguard boats have been dispatched to the scene, while ambulances have been stationed on the beach ready to receive rescued passengers.

Üstel wrote on social media that the “priority right now is human life”, adding that security forces, rescue teams and health officials were all on the scene.

He added the disaster will be thoroughly investigated and “even the slightest negligence will be uncovered”.

“No one will be spared, regardless of who they are, who is found to be at fault or responsible,” Üstel said.

Erhan Arikli, the transport minister of the self-declared Turkish Republic of Northern Cyprus (TRNC), which is only recognised by Turkey, told local media that 100 passengers had been taken to shore.

Turkey’s President Recep Tayyip Erdogan sent his condolences to Turkish Cypriots and said efforts to reach those who were still missing “continue uninterrupted”.

“Immediately after the accident, we launched extensive search-and-rescue operations in co-operation with the authorities of the Turkish Republic of Northern Cyprus,” he said at a military ceremony on Sunday.

Mustafa Koc saved around 65 people with his boat after the vessel capsized. He told the BBC that he felt the crew should have waited until the sea was calm.

“It wasn’t safe for them,” he said. “The sea was quite choppy.”

Koc added: “People died. It’s not right.”

He said the boat had arrived in Kyrenia on Saturday and “had some damage in the front”.

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

On Sunday evening, Arikli told TRT the ship had completely sunk.

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

A hotline has been set up to provide passengers’ relatives with information. The nationalities of those who were aboard and the status of the injured are unclear.

Local television has broadcast images of the upside-down ferry in the water, with people wearing life vests atop its hull.

The TRNC, which is recognised only by Turkey, controls the northern third of the island of Cyprus, which has been divided since 1974.

Additional reporting by Sherie Ryder