Two men were seriously assaulted by a gang after one of them tried to stop an argument in a McDonald's.
Police said the violence spilled out the restaurant in Jamaica Street at about 01:00 on Saturday.
The victims, aged 23 and 25, were then attacked on the street outside.
The incident happened just five hours after a 16-year-old boy had his head stamped on by a gang near the same McDonald's.
Police said the 23-year-old was attacked inside the restaurant after he intervened to stop a dispute.
He suffered a facial injury and damage to his teeth.
The disturbance then continued outside nearby Currys PC World.
When the victim's 25-year-old friend intervened he was also attacked by the suspects and suffered facial injuries.
The injured men sought refuge at the Euro Hostel in Clyde Street and were taken to Glasgow Royal Infirmary. Both were treated then released.
PC Paul Hendry said: "I know that Jamaica Street was busy at the time this disturbance took place and therefore I'm certain that there would have been many people who witnessed the two men being assaulted."
One of the men is described as white, age 16-17, 5ft 11in, with short brown hair. He was wearing a dark blue jumper and black jeans.
Another suspect is described as white with ginger hair. He was wearing a yellow jacket and black jeans.
Police said a third man is white, aged 20-30, 6ft 1in to 6ft 2in, of slim build and with short, dark hair. He was wearing a black tracksuit.
The final suspect is only described as tall, of stocky build and was wearing a hooded jacket.
The suspects were also in the company of a woman, who did not get involved in the incident.