A member of the south London drill group Harlem Spartans has become the third young man to be stabbed to death in the capital in a little over 12 hours.

Crosslom Davis, 20, also known by his rap name Bis, was the second Harlem Spartans member to be stabbed to death. He used to perform alongside Latwaan Griffiths, who was murdered in August 2018 at the age of 18.

Davis, 20, was pronounced dead at just after 3.30am on Friday in Deptford, south-east London about 12 and a half hours after Exauce Ngimbi, 22, was killed in an unrelated attack in Hackney, east London. A third unnamed man, 26, was knifed to death in a suspected robbery near Harrods in Knightsbridge, west London as he made his way home from a restaurant just after midnight. He was found unconscious with a stab wound to the back.

Another man was knifed in the same attack, believed to have been carried out by two males attempting a robbery. He remains in hospital, where his injuries are described as not life-threatening.

Harlem Spartans, who regularly rapped about violence and knifings, have achieved prominence with Davis’s latest song attracting close to a million views on YouTube. They were championed by Tim Westwood when they performed on the former Radio 1 DJ’s YouTube channel in 2017.

England footballer Jadon Sancho, 19, led tributes online to Davis tweeting: “Rest up bis.”

DCI John Massey said: “While we tirelessly work to piece together the events that sadly led to a young man losing his life, I would appeal to those who have information to do the right thing and speak to us.”

Speaking outside Scotland Yard on Friday afternoon, Commander Jane Connors said the killings were not linked to one another.

She added: “Each of these attacks is a tragedy – not just for the victims and their families but for the wider communities who are left reeling by this senseless violence. Our highly experienced teams of investigators are working relentlessly to determine exactly what happened and bring those responsible to justice.”

“Over the weekend, residents will see more officers on patrol in the areas where these murders took place as well as other parts of London. This highly visible policing presence will include officers from our reserve units … and armed units.”

Last year, there were 141 police-recorded homicides in the capital – the highest in a calendar year since 2008 – according to Home Office statistics.

Speaking about the investigation into the Knightsbridge attack, Ch Insp Andy Partridge said: “It appears that the victims were going home having just attended a nearby restaurant. They were approached by two males on Basil Street at the junction with Pavilion Road. It was here that the two male suspects confronted the victims.

“Although at an early stage, we believe that the victims were approached in order to steal property from them and were attacked during that encounter.”

The luxury department store was open on Friday, while a crime scene remained in place.

Scotland Yard has arrested three men, one aged 23 and two aged 26, and a 14-year-old boy, over the murder of Ngimbi.

DCI Paul Considine said: “Exauce’s family are devastated but I want to assure them, and the wider public, that we will work tirelessly to ensure those responsible for this murder face justice.”