History teacher James Furlong, 36, scientist Dr David Wails, 49, and Joseph Ritchie-Bennett, 39, who worked for a pharmaceutical company, were murdered in Forbury Gardens on June 20 last year.
PC James Packman, Sgt Iain Watkinson, PC Liam Steele and PC Liam King stepped in unarmed to catch and detain Khairi Saadallah following the attack.
The officers’ bravery is to be celebrated alongside ten other colleagues at Thames Valley Police’s Annual Bravery Awards on Thursday.
PC Packman, who had only been an officer for two years, was off duty in Forbury Gardens when the chaos unravelled. He immediately ran after the attacker.
“I was sitting on the grass, facing towards where the victims were. I don’t know what got my attention first, I think it was a scream,” he said.
“I looked up and there was the suspect and he was going around the group who were sitting on the floor, stabbing them. I shouted ‘knife’.”
PC Packman said “adrenaline took over” as he chased the attacker out of the park while calling for backup, which brought the other three officers to the scene.
“I just did what I thought was best to do at the time. My first thought was just to keep an eye on him and make sure he doesn’t get away,” he added.
Unarmed response officers PC Steele, PC King, and Sgt Watkinson saw Saadallah running towards them, “rugby tackled” him to the floor and restrained him.
PC Steele recalled seeing the suspect “running down the road with blood covered all over his hands.”
Three other people – Stephen Young, 51, Patrick Edwards, 29, and Nishit Nisudan, 34 – were also injured before Saadallah threw away the 8in knife and ran off.
Craig O’Leary, chairman of Thames Valley Police Federation, hailed the four officers as “complete and utter heroes.”
He said: “This man was a terrorist. These officers were unarmed and stopped him in his tracks before he could cause anyone else any harm.
“The actions of James – who let’s not forget was off duty – Iain and the two Liams were exemplary and in the highest standards and traditions of the British police service.
“They acted selflessly and with immense bravery in order to protect the public from the possibility of further attacks. We could not be prouder of them.”