A man was rushed to hospital with “serious injuries” following an attack at a home in Dumbarton.
The 40-year-old received emergency treatment at Queen Elizabeth University Hospital in Glasgow following the incident on Sunday morning.
Police rushed to the scene on Murroch Avenue in the town shortly after 9.15am after reports of a disturbance.
Three men, aged 40, 18 and 17, were arrested in connection with the incident and released pending further enquiries.
A probe into the incident is now under way.
Detective Constable Thomas O’Donnell, of Clydebank CID, said: “Our enquiries into this incident are ongoing and I would urge anyone with information to get in touch.
“We would be keen to speak to anyone who may have seen or heard any disturbance in the area, or any local residents who have any information that could assist our investigation to contact us.
“Anyone with information should call police via 101, quoting reference 1314 of September 4, or call Crimestoppers anonymously on 0800 555 111.”