A 14-year-old boy screamed for his mum just moments before his death after two teens stabbed him with machetes.

Kelyan Bokassa made his desperate plea to a stranger who tried to help the boy after he had been repeatedly stabbed on the bus 472 in Woolwich, southeast London.

The aspiring rapper screamed for help when two teens stabbed him 27 times during the 14-second attack on January 7.

The boys, aged 16 and who cannot be named, had boarded the bus shortly after Mr Bokassa carrying identical machetes concealed in their clothes.

Chilling footage showed how the pair walked towards Mr Bokassa, withdrew their blades and began stabbing him in cold-blooded silence.

Mr Bokassa’s last words were ‘take me to my mum’s. I want my mum,’ before he collapsed at the back of a bus as fellow passengers tried to help him.

The two boys were ‘smiling’ as they stabbed Mr Bokassa, Deanna Heer KC, the prosecutor in the murder case, told the court today as the youths were sentenced.

They have both now been handed a minimum of 15 years and 10 months in prison for murder, as well as a 12-month sentence for possessing a knife which will run concurrently.

Both boys pleaded guilty to Keylan’s murder at the Old Bailey in May.

Ms Heer said: ‘Since Kelyan Bokassa was seated on the back seat, he was cornered, unable to escape as the defendants repeatedly thrust their knives towards him, smiling as they did so.

‘Kelyan Bokassa had no time to reach for his own knife, which remained in his trousers, and instead tried in vain to protect himself with his school bag.

‘There were several other passengers on the top deck who fled in panic when they realised what was happening. They describe hearing intense screaming from the back of the bus and the victim shouting, ‘Help. Help. I’ve been stabbed’.

‘They describe both defendants making quick, forceful movements towards Kelyan Bokassa as he tried to defend himself.’

Marie Bokassa, the boy’s mum, said in a victim impact statement: ‘At least my son is at peace, and those two kids are going to have a really tough time.

‘

‘I ask myself what has happened to those two boys that has resulted in that terrible act of violence, and I cannot imagine how can they be so angry.

‘What they did was horrific and I do not know what has led them to do this, and maybe I will never.

‘He would put music on and we’d dance together in the living room.

‘He loved Mr Bean, which we watched together, and he would laugh. I miss his laugh, miss his voice.

‘I will never see his children or be a grandmother and he will never have his own family.’

The heartbroken mum said she had spent her son’s 15th birthday at his graveside.

The defendants were identified from CCTV footage of the bus and arrested quickly following the fatal attack.

One of the machetes was recovered from the River Thames.

The boys showed no visible reaction in the dock during the hearing, while members of the public sobbed loudly as footage of the attack was shown.