Detectives believe an aspiring lawyer who was stabbed to death as he went to buy a bagel was subjected to an “unprovoked attack” by a group of six young men.

A 19-year-old man and a 17-year-old boy arrested on suspicion of murdering 22-year-old Sven Badzak in Kilburn north-west London, last Saturday have been released on bail.

Mr Badzak, who was working for his father’s construction company and hoped to do a law conversion course, was waiting outside a bagel shop with his 16-year-old friend when the pair were attacked.

His mother, Jasna Badzak, a former Conservative Party activist, said she believes her son was killed in a random attack.

Detectives do not believe the victims knew their attackers and have no information to suggest it was a robbery.

Detective Chief Inspector Mark Wrigley said on Friday: “At the moment we have no other information than that. It was an unprovoked attack, certainly.

“It happened very, very quickly and Sven and his young friend were attacked for no reason that we know of at this time.

“There were six who attacked the two young men. The two who have been arrested have now been released on bail.

“We are still conducting our inquiries to confirm the identity of all of those who took part.

“This group of young men came to that area and moved together as a group before the offence.

“The offence took place, I believe they left initially in a group together as well, so I believe they acted together.

“The group of males have been described as a mixture of white males and black males and that’s the descriptions varying from different witnesses at the moment.”

Ms Badzak said her son, who was privately educated at Wetherby and Portland Place schools before attending Roehampton University, had gone to a shop to get orange juice and then to a bagel shop when he was attacked.

As he and his friend were chased at around 5.30pm, they became separated and Mr Badzak, from Maida Hill, west London, fell to the ground and was stabbed repeatedly.

The 16-year-old also suffered multiple stab injuries but managed to escape into a shop in Willesden Lane. He is currently in a stable condition in hospital.

Making a fresh appeal for witnesses, Mr Wrigley said: “We’re approaching a week since the offence took place. We have arrested two people, but we still need some more information about who was there that evening and what took place.

“We know there were a lot of people out on foot who may have witnessed this on the evening of the offence, but also people were passing in vehicles.

“I’m seeking information from those people and would ask them to come forward.”

Ms Badzak said her son, who had a degree in sociology but wanted to become a lawyer, had met Boris Johnson and other well-known Conservative politicians when he was younger through her campaigning work with the party.

The Prime Minister said “absolutely everything” is being done to tackle violent crime after Ms Badzak, a consultant and financial analyst, called on him to help ensure her son’s killers are caught.

Meanwhile, an 18-year-old man was stabbed to death in a fight near Parsons Green Tube station in south-west London on Thursday evening.

Mr Wrigley said there will be extra patrols in areas where violent attacks have been carried out.

“We are doing everything we can in terms of dealing with young people who think it’s okay to go out on the street with knives,” he said.

“Statistically, if you carry a knife, you are more likely to be a victim and obviously you’re more likely to use it, so don’t do it.”

Witnesses to the attack on Mr Badzak are urged to call 101 or contact Crimestoppers.