Face of Nation : The officer, identified only as BX44, said he and two colleagues had arrived at the scene on the evening of 3 June 2017 to see three Asian men with large knives coming from a crowd “closing us down”.
Khuram Butt, 27, Rachid Redouane, 30, and Youssef Zaghba, 22, were killed by police 10 minutes after they began a van and knife attack which left eight people dead and 48 injured.
Inquests for the three men at the Old Bailey heard BX44 said he had first fired at Butt because he thought Butt was about to kill his colleague BX46.
BX44 said: “The red dot [from the gun’s sights] was on him but there was very little reaction and I was surprised he was still coming.
“I continued to track him and fire shots until I had to break away to deal with Rachid Redouane who at this point was closing us down and was about to kill another colleague, BX45.
“The red dot was on him. I fired shots and there was no immediate reaction. I carried on firing until I had to deal with the third threat of Youssef Zaghba who was on top of me.
“I was backing away trying to create a reactionary gap when I fired and fell backwards and as I fell backwards I fired and from the floor I fired through my legs up to his chest.
“I thought he was about to kill me.”
Afterwards, he kicked Zaghba’s hand away from his chest, assuming he was about to detonate an explosive belt, before moving on to support BX46, he said.
BX44 said that, minutes after the first burst of gunfire, he saw Butt’s chest rise and fall.
He said: “I did not see his hands but his arms started to move down slowly towards the suicide vest.
“I thought he was going to detonate. I fired shots. They were aimed shots.”
Earlier BX46, who qualified as a firearms specialist in 2013, had told the inquest about the moment Butt had come towards him with a knife “in a raised position”.
He said: “I formed the view he was an immediate threat to me and I would have said words to the effect ‘armed police, stand still, drop the knife’.
“I believe his intention was to use the knife and stab me, kill me and get hold of my weapons.
“The knife was in a raised position, which gave me great concern.
“At this point I was aware that around his torso he was wearing an improvised explosive device.
“I already knew he had a knife and he was a threat to my life but now he was an even bigger threat, even with one or two metres, a detonation would be fatal to colleagues, members of the public, anyone in the location.
“So I aimed my rifle towards the male and I was moving back quickly and I moved the fire selector lever to fire and I pulled the trigger.”
BX46 told jurors that he fired a “number of shots”, stopping “when the male fell to the floor in front of me”.
He added: “I used lethal force to avert the danger of him detonating his device. I took an aimed shot to his head.”
Between them, the firearms officers and their colleague BX45 fired 31 shots.
The inquests continue.
