A PSNI spokesperson said that shortly before 3.45 am police received a report that a man had been assaulted after an incident in the vicinity of Brownstown Road in Portadown.
The man, aged in his 30s, was taken to hospital for treatment for his injuries.
Three males, aged 27, 32 and 43 were arrested a short time later and remain in police custody at this time.
Police remain in the area this morning conducting enquiries into the incident.
Disruption will be kept to a minimum and police appreciate the understanding of the community while the investigation continues.
Detectives are appealing for anyone who was in the vicinity of Shamrock Park or Brownstown Road early this morning and who witnessed the incident to contact Detectives in Lurgan on 101 quoting reference 315 09/09/18.
Alternatively, information can also be provided to the independent charity Crimestoppers on 0800 555 111 which is 100% anonymous and gives people the power to speak up and stop crime.