Liam Spencer was with his girlfriend Stephanie and had stopped briefly to say hello to former colleagues at the hospital where he'd worked until recently.
The 21-year-old from Childwall heard the blast and knew it was too loud to be a car crash.
He ran back and forth to the car to see if anyone could be rescued.
Liam says all those around the vehicle were in shock and many did not understand his pleas to establish if anyone else was in the vehicle.
The taxi that the suspect had taken to the hospital on Remembrance Sunday morning had come to a stop right next to Liam's vehicle.
"I thought if my car goes up it will take the whole hospital so I thought I'll try and move it
"I then I realised, what am I doing in this car, my life's not worth it so I just got out."
Emergency services arrived and put out the flames and police secured the car park and front entrance of the hospital.
Liam and Stephanie, who lives in St Helens, were sat in the foyer of the hospital waiting for police to take a statement.
This, he said, took a couple of hours because officers were trying to contain the situation and make sure the hospital was still accessible to the public.Liam said: "[Stephanie] was quite shaken up. I was alright for about an hour - it hadn't really hit me.
After finding out the next day that the explosion was now being treated as an act of terrorism, Liam said he and his girlfriend were "shocked" by the news.Since the bombing, Liam said that police and intelligence services have been in regular contact.
He added: "We still can't believe it's real. My girlfriend is still suffering with her ears a lot because she was in the car.
"She's really drained from it all. I'm really drained from it myself - I'm struggling to sleep because of it.
"I keep thinking about the situation and then the adrenaline comes back to me. I just keep thinking about how it all happened so quickly."Anyone who has any information should call on 0161 856 1027 quoting Liverpool Women's Hospital incident.Details can be passed to the independent charity Crimestoppers anonymously on 0800 555 111.