As flames tore through a 12-story hotel at a popular ski resort in northwestern Turkey, friends Esra Karakisa and Halime Cetin stood helpless as the horror unfolded before them, with people leaning out of smoke-filled rooms pleading for help and others making the harrowing decision to jump.

At least 66 people were killed and 51 injured as a fire ripped through a ski resort hotel in northwestern Turkey on Tuesday, according to the country’s interior ministry.

In the aftermath of the incident, Turkish President Recep Tayyip Erdogan announced a day of national mourning to be observed on Wednesday. Rescue teams and local authorities are investigating the cause of the fire,