40-year-old football coach, Tunde Fadayomi was stabbed to death during a fight in Willesden, north London, on Thursday evening.
According to The Mirror UK, an eyewitness said Fadayomi was protecting his son, who is believed to be 14, after he was threatened on a bus before a row spilled into the street.
Harrowing video footage being circulated on social media shows Mr Fadayomi being fatally stabbed.
Metropolitan Police said they arrested a 42-year-old man at his home address in Willesden on suspicion of murder of the single dad on Friday.
He is being held at a police station and Scotland Yard say they are not searching for anyone else in connection with Mr Fadayomi’s death.
Police said Mr Fadayomi’s next of kin have been informed.
DCI Claire Hine, investigating officer, has appealed for people not to share the footage and for witnesses to come forward.
She said: “Foremost in our thoughts are the victim and his family, who are coming to terms with his very sudden and violent loss.
“My specialist officers are providing them with support at this very sad time.
“At this early stage in our investigation we believe the incident started on a Route 260 bus. It continued out onto the High Road and into a fast food shop in front of a number of horrified onlookers in the street, and on the bus.
“I know there are videos circulating on social media that feature some incredibly distressing images and I ask that people please refrain from sharing these to avoid causing the victim’s family any more trauma.
“We’ve spoken to a number of people who have told us what they saw, but there are others who have yet to make contact. I would ask those witnesses to call us, so that we can fully establish the chain of events that has led to a man losing his life in such a horrific way.
“I’d also like to acknowledge that this incident would no doubt have caused incredible panic and alarm to the people who saw it.