A man in his 40s is in a serious condition after a fire broke out at Grove Hotel in Bournemouth.
He was taken to hospital for treatment on Sunday morning from the property in Grove Road.
A cordon has been put in place and detectives are liaising with the fire service to establish the full circumstances of the incident.
The cause of the fire has not been confirmed at this time.
Detective Chief Inspector Andy Bell, of BCP CID, said: “Our enquiries into this incident remain ongoing and I am appealing to anyone who saw or heard any suspicious activity in the area to please come forward.
“Also, I would like to hear from any residents or motorists in the wider area who may have captured anything of relevance on home CCTV or dashcams that may assist my investigation.”
Anyone with information is asked to contact Dorset Police by calling 101, quoting occurrence number 55240017893.