A fire at a hotel at a popular ski resort in northwestern Turkey on Tuesday killed at least 66 people, Turkey's Interior Minister said.

Ali Yerlikaya said at least 51 other people were injured in the disaster.

"We are in deep pain. We have unfortunately lost 66 lives in the fire that broke out at this hotel," Yerlikaya told reporters after inspecting the site.

Health Minister Kemal Memisoglu said at least one of the injured was in serious condition.

The fire broke out at around 3:30 a.m. in the restaurant of the 12-story Grand Kartal hotel in the resort of Kartalkaya in Bolu province, officials and reports said. The cause of the fire was under investigation.

Two of the victims died after jumping from the building in a panic, Gov. Abdulaziz Aydin told the state-run Anadolu Agency. Private NTV television said some people tried to climb down from their rooms using sheets and blankets.

There were 234 guests staying at the hotel, Aydin said.

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Necmi Kepcetutan, a ski instructor at the hotel, said he was asleep when the fire erupted and he rushed out of the building. He told NTV television that he then helped some 20 guests out of the hotel.

He said the hotel was engulfed in smoke, making it difficult for guests to locate the fire escape.

"I cannot reach some of my students. I hope they are OK," the ski instructor told the station.

Television images showed the roof and top floors of the hotel on fire.

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Witnesses and reports said the hotel’s fire detection system failed to operate.

"My wife smelled the burning. The alarm did not go off," Atakan Yelkovan, a guest staying on the third floor of the hotel, told the IHA news agency.

"We tried to go upstairs but couldn’t, there were flames. We went downstairs and came here (outside)," he said.

Yelkovan said it took about an hour for the firefighting teams to arrive.

"People on the upper floors were screaming. They hung down sheets ... some tried to jump," he said.

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The government appointed six prosecutors to lead an investigation into the fire. NTV television suggested that the wooden cladding on the exterior of the hotel, in a chalet-style design, may have accelerated the spread of the fire.

The 161-room hotel is on the side of a cliff, hampering efforts to combat the flames, the station also reported.

NTV showed a smoke-blackened lobby, its glass entrance and windows smashed, its wooden reception desk charred and a chandelier crashed to the ground.

Kartalkaya is a popular ski resort in the Koroglu mountains, some 300 kilometers (185 miles) east of Istanbul. The fire occurred during the school semester break when hotels in the region are packed.

Aydin's office said 30 fire trucks and 28 ambulances were sent to the site.

Other hotels at the resort were evacuated as a precaution and guests were placed in hotels around Bolu.

Meanwhile, a gas explosion at a hotel at another ski resort in central Turkey injured four people.

The explosion took place at the Yildiz Mountain Winter Sports Center in Sivas province. Two skiers and their instructor were slightly injured while another instructor received second-degree burns on the hands and face, the Sivas governor’s office said.