We were just finishing lunch in Pret a Manger on Queen Street when the screaming started.

There was a sudden commotion outside on the street and one of the customers nearer the window shot out of his seat and started shouting: "Call an ambulance. Someone call an ambulance."

Another was yelling: "Oh my God, oh my God."

There was a series of thuds from outside and continuous screaming. It's such a busy junction and I assumed someone had been hit by a car.

I have first aid training so I ran out in the street to see if I could help.

The first few seconds were so confused. There were people lying in the road and debris strewn everywhere but the junction, at the corner of St Vincent Place and Queen Street, was empty.

My attention was focused on the people in the road but when I glanced along Queen Street there were cars fanning out on each side of the road, the way drivers do when an emergency vehicle needs to get through, and a bin lorry coming to stop at the train station.

At that point, though, I wasn't able to take in the wider scene. There were three people who needed help.

One was the most obviously seriously injured and I went to them but other passers-by came to help, saying they were medics, and I left them to it. A second person was also surrounded by people who were trying to help.

The third had people standing around her but no one seemed to be helping or taking control of the situation. She was barely conscious and injured and I worried I would be able to provide little help but comfort.

However, fortunately, she came to. I don't want to go into detail about what happened when I was with her because it's her story, not mine, to share.

I think I might have been with her around 40 minutes before she was taken away in an ambulance. I wonder if she will remember me and I hope she doesn't.

While I was with her the two other casualties on each side of us died. People took off their coats to lay over their faces before blankets were brought.

I didn't look beyond these three people for a long time but when I did, the scene was bizarre. So many ambulances had appeared, so many police cars and fire appliances and I hadn't really noticed them coming.

It is a cliche, but it was like a film set.

There were so many people there who had very narrow and very lucky escapes. My friend and I were just leaving Pret when I decided to run to the loo. My dodgy kidneys are the bane of my life but if I hadn't hesitated, we would have been out in the street when the bin lorry went past.

Maybe in any city, at the scene of such devastation, people would run to escape trouble but I really think Glasgow is special.

So, thank you to the man who put his cardigan over the girl in the road; thank you to the man who draped a blanket over me.

Thank you to the staff in Pret who let me wash the blood from my hands and gave me coffee. Thank you to the kind couple with their son, who is a very, very brave young man.

And thank you to the emergency services, who were so efficient and empathetic. Having seen what I saw on Monday afternoon I am reminded yet again what we owe them.