Bullet cartridges scattered in the street of a residential neighbourhood in Buenaventura, Colombia. [AFP]

Eighteen-year-old Toulwalase Odunewu received a 29-year jail term and Michael Tommy-Mbogba, 21, was jailed for 23 years. The other two, aged 16 and 17, were given detention orders of 16 and 23 years.

They will be served in youth custody until they are 18 when they can be transferred to an adult jail.

The sentences come after a ban on "zombie"-style hunting knives with blades of over 20 centimetres (eight inches) came into force late last month.

The ban aims to curb the alarming rise in the number of knife killings, described as a "national crisis" by Prime Minister Keir Starmer.

Kukabu was one of 21 teenagers who met violent deaths in the British capital last year: of those, 18 were stabbed.

Detective Chief Inspector Laura Semple said knife crime was having a "devastating impact on our communities".

"That's why we're committed to doing everything in our power ... to protect young people and make London safer," she added.