The man who injured six people including a police officer during a stabbing frenzy warned he would carry out the attack the night before, ITV News has learned.
Scotland Correspondent Peter Smith has spoken to friends of the attacker, who have identified him as a Sudanese asylum seeker in his 20s named Badradeen.
They said Badradeen told friends of his plans to attack on Thursday evening, and they then told the Park Inn Hotel - where the attack took place - about his threats.
Siraj, who spoke to the attacker, says he was warned of stabbing plans the night before the attack
On Friday morning, a call was organised with Badradeen and his solicitor to discuss his concerns. It was after that phone call the stabbings took place. He was then shot dead by armed police at the scene.
A man, who gave his name only as Siraj, said he was informed of the attack the night before.
Siraj said: “He said ‘I will attack’ so everyone should take it seriously. He said to me. I told him ‘no, there’s no need to attack’ and he said ‘they hate me, I hate them, they are against me’.
"He started to say a lot of stuff like that but I said nobody hates you, nobody knows you, nobody knows each other.
“I reported him to the hotel reception and then the next day, yesterday morning, the housing manager talked to me and I said to him everything he (the attacker) said to me. And in the afternoon, it happened.”
ITV News has contacted the Park Inn Hotel for comment.
Among the injured was 42-year-old police officer David Whyte, who is in a stable condition. Two teenagers were also injured, including a 17-year-old from Sierra Leone, ITV News understands.
In a statement on Saturday, Constable Whyte credited the "swift actions of colleagues" for saving his life and containing an "extremely challenging" situation before it could escalate.
He said the attack was "something I will never forget".
In a statement posted on Twitter, he said: “The incident myself and colleagues faced in West George Street was extremely challenging. The scene we were confronted with is something I will never forget.
“As the first responders on scene, myself and my colleague did what all police officers are trained for to save lives.
"Despite suffering serious injuries myself, I know that the swift actions of colleagues saved lives and prevented a far more serious incident."
Police have not yet confirmed the identity of the other victims, but said they were men aged 17, 18, 20, 38 and 53.
Officials are not looking for anyone else in relation to the incident, police have said.
Housing charity Positive Action in Housing said the hotel was used to house asylum seekers and that there were between 80-100 people living there, from countries including Iran, Somalia and Afghanistan.
One resident who asked not to be named, told ITV News he was one of the first on the scene and helped those who were wounded.
"The lift was covered with blood on the floor," he said.
"So I did not take the lift, I went down the stairs. When I reached down to reception there was blood everywhere on the reception floor and the whole area, covered with blood. So then I've seen one of the receptionist, fighting for his life behind the receptionist desk. So I shouted at him and told him to stay calm as possible.
"And I called for help. I ran outside the hotel and that's when I saw another receptionist who was lying down on the stairs, always has been stabbed and gasping for air."
"We heard the screaming and the commotion of everything," eyewitness Matthew Nesbitt told ITV News.
"I saw one gentleman lying on the steps outside the hotel. And he had a stab wound to the torso and it was a lot of blood on the steps."
Another witness, who gave his name as Craig, said he saw a man lying on the ground who looked as if he had been stabbed.
"Following that I saw the armed response moving into the building. I then saw many victims being ushered out and being taken away," he said.
"The first few moments there wasn't a level of fear from anyone around us. I think it's one the things about Glasgow people move towards commotion rather than move away from it. But when we saw the armed police on the scene and we got shouted at to move back, it all got a bit more seriously."
Scottish First Minister Nicola Sturgeon said she was "shocked and saddened" by the incident.
"This had been a dreadful afternoon for the city of Glasgow," she said.
Ms Sturgeon said people’s thoughts should be with those injured.
She said: “All of us should bear them in mind, bear their families in mind and make sure we focus on all of the great things that bring our city together.”
The First Minister continued: “These are incidents that shock all of us and leave a sense of anxiety.
“The police through their professionalism and calm handling of this contained this situation relatively quickly.”
She said the actions taken ensured a “very, very serious incident didn’t become much worse”.