He was rushed to hospital but died from his wounds.
An eyewitness said the man had run past him in a blood-soaked t-shirt, crying out for people to call the police.
Another eyewitness, the assistant manager of the nearby cafe A Poke Theory, said the victim had collapsed on the floor outside the store in a pool of blood.
She called the police.
Then, the alleged attacker walked into the store, calmly placed the 10-cm knife he was holding on a food tray there and stood there waiting for police to come.
The assistant manager locked the front doors of the store and ushered customers to the exit at the rear of the shop.
Another eyewitness who saw the attacker, a man who’s in his 60s, said he was “very neatly dressed” and looked calm, as though he was prepared to be arrested.
Police officers subsequently arrested the man.
Investigations are ongoing.