: "They got to the door and one of them said 'I've been stabbed'.
"He ran into the bar and I followed him in. He fell to the floor. I shouted to the girls to get me some towels and phoned 999 to get an ambulance.
"I put pressure on him. I was talking to him, trying to keep him with us, saying 'what's your name, what's your mum's name, what's your address', trying to keep him talking.
"I kept the pressure on his wound. He was crying, I was saying 'it's going to be five minutes, you'll be fine'. When they got here, they worked on him and put him on a stretcher.
"We did everything we could for the lad."
Officers are appealing for anyone with information or who saw the attack to come forward and a police cordon remains in place.
Detective Superintendent Lewis Hughes, appealing to the public for information about the attack, said: "I'd like to reiterate that our thoughts remain with the family and loved one's of the young man who was very sadly killed yesterday afternoon.
"This has been a fast paced investigation and I am pleased to say detectives have made three arrests overnight in connection with his death.
“Although they remain in custody for questioning our investigation is still in its initial stages and we are continuing to appeal to anyone who may have been in the area at the time to come forward and assist police.
“This incident occurred in broad daylight in a Bury town centre so it is highly likely there are members of the public who witnessed the assault or may have mobile phone footage from around the town.
“If you were in Bury town centre and saw any disturbance in or around Millgate Shopping Centre then we ask that you contact Greater Manchester Police. You can also pass information anonymously via Crimestoppers.
"This is shocking incident of violence and I want to assure the public we are continuing to work at pace to ensure those responsible face justice and we provide this young man's family with the answers they deserve."
Anyone with information is asked to contact Greater Manchester Police quoting incident reference 1940 of 11/03/22 via 0161 856 0027 or gmp.police.uk.
Alternatively, people can call Crimestoppers, anonymously, on 0800 555 111.