Police were called to the station on Monday (July 28) just after 8.40am to reports of the attack.
A man was taken to hospital with serious injuries, which since are not thought to be life threatening.
Overnight, the investigation has been ongoing and officers have been making arrest enquiries.
In one video, a man who appears to be injured and laying face down on the floor was shown, with far-right activist Tommy Robinson allegedly seen walking past.
Robinson had also filmed himself that day while walking in the station.
A British Transport Police spokesperson said: “Officers were called to St Pancras station just after 8.40pm yesterday (28 July) following reports of an assault.
“Officers attended and a man was taken to hospital with serious injuries, which are not thought to be life threatening.
“Overnight the investigation has been ongoing and officers have been making arrest enquiries.
“Anyone with information or who witnessed what happened can text 61016 quoting reference 655 of 28 July.”
