After he and his comrades beat and subdued the suspect, they caught sight of a what they feared was an explosive vest.
"I was driving, I stopped the car and ran towards it," said Hurst, of North London. "I don't know why I ran over.
"There were about five guys there when we got there.
"I jumped in and kicked him in the head to make him release his knife. A few others did so.
"He was shouting 'get off me, get off me'.
"I was just trying to do as much as I could to get him to release the knife. We wanted to make sure we got the knife away from him as quickly as possible.
"We wanted to kick him, we wanted to kill him. Everyone was shouting."
Hurst said that the attacker was rolled onto his back to reveal what appeared to be a bomb vest, instilling fear in the members of the public who nevertheless continued to hold onto the knifeman as his weapon sprang free.
"The knife flew away. The moment they rolled him over off his chest, they saw he had a bomb vest.
"The police arrived so quickly. They told us 'get the fuck back', they had rifles. They put three rounds into him.
"He was still lying there for about five minutes sorting himself out, trying to cover himself with his jacket."
Hurst made his way home shaken and in disbelief after the incident on the bridge, returning to his partner of eight years.