Four men have been seriously injured and a woman has also been treated in hospital after fights outside a house party in Renfrew.
Police were called to Cardon Square in the town at about 05:30.
They said a number of men and women in their late teens to mid-20s made off in different directions when officers arrived.
Others were treated for injuries at the scene. Detectives appealed for anyone with information to come forward.
Det Insp Scott McCallum said: "This was a serious disturbance involving a large number of individuals participating in a series of fights. From what we understand at this time, the incident stems from a disagreement within a flat being used for a party.
"At this time, four men, aged in their late teens to mid-20s, remain at the Royal Alexandra Hospital in a stable condition following treatment for serious injuries.
"One woman was released from hospital following treatment.
He added: "Violence of this nature within our communities will not be tolerated. We have a large team of officers working towards tracing those involved in the incident. We are analysing available CCTV, conducting door-to-door enquiries and searching the local area."
