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.

Turkish President Recep Tayyip Erdogan says the number of suspects detained in connection with the deadly hotel fire at a ski resort has increased to 14.

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

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.