Police investigating the London Bridge terrorist attack have released images of the fake explosive belts worn by the three perpetrators and which officers believe may suggest the terrorists planned to create a “siege situation”.

All three of the attackers wore leather belts that were attached to disposable water bottles wrapped in silver masking tape, an attempt to replicate a suicide bomb belt and maximise the fear of anyone who approached.

Dean Haydon, the Metropolitan police commander who is leading the counter-terrorism investigation, said the fake suicide belts made the courage of police and members of the public who confronted the terrorists even more remarkable.

In a statement, Haydon said: “I have not seen this tactic in the UK before where terrorists create maximum fear by strapping fake explosives to themselves. Anyone who saw them on the night would have thought they were genuine. It is hard to speculate what the motive was for wearing the belts. It could be that they had plans to take the attack into a siege situation, or it might be that they saw it as protection from being shot themselves.

“It makes the bravery of those police officers and members of the public who tackled the terrorists even more remarkable. The belt would have been visible to them and if you are fighting back or aiming a shot at someone wearing the device you would clearly be very aware that you could be caught in an explosion.”

Detectives have so far spoken to 262 people from 19 different countries and, of these, 78 are considered significant witnesses although officers are appealing for more to come forward. One specific appeal centres on the distinctive pink ceramic knives which the attackers used to stab dozens of people during an eight-minute rampage last Saturday.

Pink ceramic knife found hung on Khuram Butt’s arm after the London Bridge terrorist attack. Photograph: London Metropolitan Police Handout/EPA

The kitchen knives, each measuring 30cm, were branded Ernesto with duct tape wrapped around the handles and in the case of the ringleader, Khuram Butt, 27, a leather strap had been attached to the handle and was hung around his wrist.

Meanwhile, yet another tale of immense courage has emerged from the attack with one of the Met’s first officers on the scene revealing his harrowing account of events. Inspector Jim Cole, 41, who works for Southwark Safer Neighbourhoods, was finishing his shift and preparing to go home to his family when the call came in that a van had ploughed into pedestrians on London Bridge.

At Borough Market the scene was so chaotic that when armed police began shooting, Cole believed it could have been the attackers. “I asked my officers to form a cordon to stop the public from going into the market and that’s when the shooting started just behind us. We had no idea what was going on, we didn’t know if it was us shooting or if the bad guys had guns.”

Realising a number of casualties were lying on the ground and that the public were petrified, Cole decided a nearby pub would be the safest place for people to shelter.

“I saw a few injured people who were bleeding, including a man who had been stabbed in the stomach and we got them to safety in the pub. I then heard more shouting and a stream of people came out of the market screaming and panicking. I got them to go into the pub’s basement as a place of hard cover.”

Cole went back outside to help the wounded and make sure police cars began ferrying stab victims to hospital. The officer also revealed how the large crowd that had gathered in the pub basement began clapping when he told them that the situation had calmed down.

“I spoke with the 200 frightened people in the basement and told them that there were armed officers outside, we were safe and we would evacuate them as soon as we could and I got a big round of applause. That was a really nice, unexpected moment. It was a nice touch.”

Early on Saturday morning counter-terrorism police made more raids in east London and a further arrest. A 28-year-old was arrested in Barking on suspicion of terrorist offences. Six other men remain in custody in relation to last Saturday’s attack.