PC Wayne Marques has spoken publicly for the first time since the night of the devastating terror attack which left eight dead and 48 injured.
He revealed that at one point he thought was going to die after being stabbed multiple times by the attackers armed with knives and fake suicide vests.
The British Transport Police officer was near the start of his Saturday night shift and on patrol with a colleague in the area of London Bridge Station when he first heard the screams.
He said he knew something was wrong when he saw bouncers and customers queuing to get into a nearby bar standing "like deers in the headlights".
The 38-year-old, who was born in Birmingham and now lives in south London, initially thought the disturbance was a pub fight that had spilled out onto the streets or maybe a gang fight "at the most".