An Army veteran who was one of the first to rush to the aide of murdered police officer Keith Palmer has told how his military training kicked in as he heard gunshots outside parliament.

"I recognised the sound," Captain Mike Crofts told The Independent. "I knew it was very close, and obviously I saw it was very close.

“Initially we took cover, I remember thinking as it happened there was a very real risk that he might have a suicide vest.”

Captain Crofts, who completed two tours in Afghanistan, then rushed to the injured officer's aid.

“We tried to open his airway, I put him in the recovery position. I tried to do an assessment of the casualty - my experience in Afghanistan taught me it is really important to get timely information and get control of the situation and I realised I was the person there to have experience of that,” he said.

“I was very specific with the police that we needed air support straight away. Five to 10 minutes later the helicopter arrived - it felt like much longer. The team were continuing to administer CPR, they could not have tried more to save him.”

Despite his best efforts, PC Palmer passed away from the wounds he sustained from Khalid Masood's knife attack. Masood, 52, also died after he was shot by police.

Captain Crofts said that his military training meant he has developed certain “coping mechanisms”. However, he said he was “in shock” after the “traumatic” experience.

Army veteran Captain Mike Crofts who served two terms in Afghanistan (Twitter)

“It was shocking and tragic," he said. "No one wants to see that or witness that, it’s really just a deeply, deeply sad event for the families who have lost loved ones.

“Having been in the army, I’ve got a lot of military friends who understand what this is like, and I have also experienced this before, so I have certain coping mechanisms.”

Captain Crofts now runs the 3 Pillars Project, a charity that works to engage young men in prisons through sport to give them more positive male role models.

His experiences in Afghanistan and his charity work have led him to believe a lot of the drivers for extremism and gang activity are the same, and he is calling for better support to be made available in the community to combat isolation and a lack of positive role models.

“People will say there is a simple solution - security and police must do better - but it isn't about them. It’s about our communities and our societies supporting each other,” he said.