Turkey has arrested 15 people as part of an investigation into a fire that killed 78 people and injured dozens at a ski resort in the Bolu mountains earlier this week, state media reported on Sunday.

Some had returned to the hotel year after year. Their deaths — amid dozens of others at the hotel — have stirred grief and outrage.

Officials in Turkey say that a fire has raged through a 12-story hotel at a popular ski resort in the northwestern part of the country during a school holiday, killing at least 76 people.

The fire, which broke out early on Tuesday, trapped many of the registered 238 guests inside, leaving 78 people dead and dozens of others injured.