Police were called to reports of a fight on Sunningdale Road in the Crosland Moor area of Huddersfield shortly after 5.15am this morning.
They found two men injured in the street.
Others were found injured on Gilbert Grove, Haigh Street and Thackeray Grove.
In all five people, three men, 26, 29 and 33, and two women, 23 and 30, were taken to hospital.
Four remained in hospital this afternoon with what police describe as serious but not life-threatening injuries.
A 26-year-old man and a 22-year-old man have been arrested on suspicion of affray and are in custody.
Police say the motive behind the outbreak of violence remains unclear.
Det Insp Ian Thornes of Kirklees CID said: “We have been conducting extensive inquiries in the local area but would urge anyone who we have not already spoken to who saw or heard anything that could help our investigation to get in contact.
“At this time the motives for and circumstances of how these people have come to be injured are unclear; however it would appear that those involved are known to each other.”
They appealed for anyone with information to call police on 101, or anonymously to crimestoppers on 0800555111.