Four gang members have been jailed for the murder of an NHS worker they picked at random “simply for the sake of it”.

Muhammad Jalloh and David Ture, both 19 and of no fixed address, as well as 23-year-old Vagnei Colubali from Cambridge were found guilty of David Gomoh’s murder in August. Alex Melaku, who could not previously be named as he was younger than 18, was also convicted.

Each was jailed for life on Friday, with Jalloh and Colubali sentenced to a minimum of 27 years, Ture to a minimum of 26 and Melaku to a minimum of 21.

Gomoh, 24, was stabbed to death while on the phone to his girlfriend on 26 April last year. He was a short distance from his home in the Newham area of east London when the attack took place and managed to stagger back there, collapsing at his front door and bleeding to death in front of his distraught family.

Sitting in judgment on Friday, the Recorder of London Mark Lucraft QC said the killers had carried out a “brutal murder” that involved a “significant degree” of planning.

He said they seemed to “kill simply for the sake of it and show little or no regard for human life”, adding: “David was a lone, innocent and entirely unsuspecting victim” who was in the “wrong place at the wrong time”. Gomoh, he said, was stabbed 10 times, with some of the thrusts penetrating almost 20cm.

In a victim impact statement, Gomoh’s mother, Marian, said she is “haunted” by recurring nightmares about what happened, adding: “I felt numb, paralysed by grief and pain. Why David?”

She said the “psychological and emotional torture escalated” during the trial, as she listened to details of what happened to her “beautiful son”.

She added that he had “so much to live for; so much unfulfilled promise and so much needed by the NHS trust he worked for to help distribute PPE and other stocks, so much humanity and compassion to share”.

She said her son’s murderers had “walked uninvited into our lives and destroyed David’s life”. The defendants have “wrecked our family … Their contempt for a human life is just beyond comprehension”.

Gomoh’s sister Lizzie paid tribute to her “fun-loving, amazing brother” and said his death has had a “devastating impact on us all”. She said: “It still feels so raw and so fresh.” Referring to her brother’s killers, she said: “I hope they will eventually show remorse.”

In a statement released after the sentencing, DCI Laurence Smith, who led the investigation for the Met police, said: “These four defendants carried out a senseless attack on a completely innocent man and there is absolutely no doubt that London is a safer place with them behind bars.”