A fire at a derelict property in Portrush, County Antrim, on Sunday night is being treated as suspicious.
Firefighters worked through the night to extinguish the fire, which was beside a nursing home.
The fire service was called to Bath Terrace just before 21:00 BST on Sunday to what was described as a "well-developed fire".
Eight fire appliances, an aerial appliance and a specialist command support unit tackled the blaze.
No-one was injured.
Police said the property "will be entered and examined by PSNI crime scene investigators once building control officials have determined it is safe to do so".
They have appealed for anyone with information to contact police.