"Gareth", not his real name, was enjoying an evening out at the Black & Blue Restaurant with his fiancee and another couple when the attack occurred, and told CNN how he spent the night inside the restaurant's bathroom as the horror unfolded amidst the sounds of screaming and crashing glass.
Gareth and his friends ran up the stairs and into a bathroom as a man, wearing a brown coat, entered the restaurant armed with what Gareth described as a "machete".
His friends, one of whom is heavily pregnant and had been due to give birth last week, followed him into the cubicle. The four of them shared the small space while trying to keep quiet, fearing they could be found by the attacker and shot through the door.
It was there that he began to message the husband of CNN's Isa Soares, a close friend, to tell him that he was trapped and to ask him to call the police.
On Sunday, Gareth spoke to Soares about his ordeal, live on air.
"It's the first time in my life that I felt it was game over," he said.
"It was looking into the fear of my friend's eyes in that one cubicle and looking at a woman who is about to give birth, seeing the fear in her eyes and trying to calm her down and not being able to make a sound because we could hear voices outside the door.
"People were walking up and down so we had to keep deathly silent. We thought we were going to get gunned down through the door. We could hear the shots outside. The fear was immense."
At least seven people died and 48 people were injured
in a two-pronged attack on London Bridge and Borough Market, with police shooting the three suspected assailants dead.
The attack started when a van rammed into pedestrians on London Bridge and ended with multiple stabbings at restaurants nearby.
Police say the suspects were shot dead within eight minutes of the first call.
Gareth, who had only booked the Black & Blue Restaurant by chance, had already experienced terror in London after being close to the Westminster attack in March.
Gareth, who lives in Chester, about 200 miles northwest of London, was in the area for one night and had chosen to dine in one of the city's most vibrant districts.
But as he was looking outside at the high street, the terror began to unfold after a what he described as a "loud bang."
"There was a bit of chaos, panic and fear in the restaurant as well because we didn't really know what was going on," he said.
"Then glass started smashing and we ran upstairs to the toilet.
"Just as I looked down the stairs, a guy had come in to the restaurant and uncovered a big knife. It looked like a machete.
"I just grabbed my friends and dashed into one cubicle with the four of us."
'Blood in the restaurant'
Scared to make a sound, the four friends remained inside the cubicle for an hour.
Unable to make a call for fear of being discovered, he sent text messages to close friends, and posted to Facebook to urge people to call the police and alert them to the attack.
It was only when they heard that the police Armed Response Team was in the building that the end appeared in sight.
But even that brought fear with Gareth worried those claiming to be the police could be imposters.
"It put the fear of God into me when I had to open the door but luckily I saw it was fine," he said.
"They took us out. There was blood in the restaurant, blood in the street. A number of people were clutching themselves.
"We then had to run 100 or 150 meters down the road. it was extremely scary."
Gareth went to hospital with his fiancee and friends. His friend, who is pregnant, is fine and the baby has not been harmed.