A fire at a ski resort hotel in Turkey's Bolu mountains killed at least 76 people and injured 51 others on Tuesday, forcing panicked guests to jump out of windows in the middle of the night.

"It was like the apocalypse. The flames engulfed the hotel immediately, like in half an hour," said Mevlut Ozer, who witnessed the incident at the Kartalkaya ski resort in Bolu province's Koroglu mountains, some 300 kilometeres east of Istanbul.

The fire began around 3:30 a.m. local time on the restaurant floor of the 12-storey Grand Kartal Hotel, authorities said.

Several fire engines and ambulances surrounded the charred, wood-fronted building, with white bed sheets tied together and dangling from one upper-floor window where people tried to flee.

"People all started to jump with panic. One friend jumped from the 11th floor — may God have mercy on him," said Omer Sakrak, another witness and employee of a neighbouring hotel.

WATCH | Drone video captures smoky aftermath: 

Drone video captures smoky aftermath of deadly Turkey hotel fire

Video provided by Reuters shows the massive emergency response after a fire ripped through a hotel in a ski area in Turkey, leaving dozens dead and many more injured.

"They tried to climb down using bedsheets. The bedsheets ripped as one friend tried ... and he unfortunately fell on his head," he told Reuters. "One father was yelling about his one-year-old child: 'I will throw my child or he will burn.'"

At least two of the victims died when they jumped from the building in panic, Gov. Abdulaziz Aydin told the state-run Anadolu Agency earlier. Those killed included Nedim Turkmen, a columnist for Sozcu newspaper, his wife and two children, the newspaper announced.

The death toll was updated from 66 to 76 on Tuesday.

Witnesses report they heard no alarms

Hotel guests told TV broadcasters they fled through smoke-filled corridors and heard no alarms.

Interior Minister Ali Yerlikaya said there were 238 guests at the hotel, which is situated at the base of several ski slopes and smouldered until the afternoon. 

"We are in deep pain," Yerlikaya told reporters after inspecting the site.

"Since the back of the hotel is on a slope, fire extinguishing efforts could only be carried out from the front and side facades," he said, adding crews began battling the mountaintop blaze about 45 minutes after the first call.

Health Minister Kemal Memisoglu said at least one of the injured was in serious condition, while 17 other people were treated and released.

Global Affairs Canada said it is not aware of any Canadian citizens impacted by the fire.

4 people detained as investigation underway

An investigation is underway into the fire, which coincided with school holidays when many families from nearby Istanbul and Ankara head to the Bolu mountains to ski.

Authorities detained four people, including the owner of the hotel, as part of the investigation, Justice Minister Yilmaz Tunc said in a post on X.

Tourism Minister Mehmet Nuri Ersoy told reporters that the hotel underwent inspections in 2021 and 2024 and that "no negative situation regarding fire competence" was reported by the fire department.

Turkish President Recep Tayyip Erdogan announced a day of national mourning to be observed on Wednesday. All flags at government buildings and Turkish diplomatic mission abroad would be lowered to half-staff, he said.

"All necessary steps will be taken to shed light on all aspects of the incident and to hold those responsible accountable," Erdogan said in an earlier address in Ankara.