A man is in serious condition in hospital after he was stabbed in Belfast city centre on Friday morning.
The incident occurred on the footbridge at the rear of the Waterfront Hall at around 11am.
Detective Sergeant Kyle Corrigan said: "Enquiries are underway and we are working to establish a motive and apprehend those responsible.
"I'm appealing to anyone who may have been in the area of the blue metal footbridge at the rear of the Waterfront Hall this [Friday] morning. Did you see anything suspicious? Did you see the incident, or any one running away from the scene?"
Police are appealing for anyone with information to contact them on the non-emergency 101 or the independent charity Crimestoppers on 0800 555 111.