A man killed outside Parsons Green Tube station was stabbed after confronting a drug dealer, Scotland Yard has said.
Omid Saidy was fatally wounded and two others were injured in the attack on Monday night.
The 20-year-old from Fulham died after confronting a drug dealer and another man who was with him, the Met confirmed.
The injured 16-year-old was discharged from hospital and arrested on suspicion of murder and attempted murder.
A 20-year-old man suffered serious but non life-threatening injuries.Image copyright Yui Mok/PA Wire Image caption
After confronting the drug dealer, the victim chased the two suspects in the direction of Beaconsfield Walk, police said.
When he caught up with the pair, he was fatally stabbed.
A 20-year-old man who was a friend of the deceased came to his aid and was also stabbed.
One of the suspects, described as a black male dressed in dark clothing, fled down Harbledown Road in the direction of Fulham Court.
The second suspect, a young white male, ran into Beaconsfield Walk.
Det Ch Insp Noel McHugh said:"A young man has tragically lost his life for simply asking a drug dealer to move on.
"I urge anyone who can assist our investigation to come forward without delay."
A post mortem examination is scheduled for Wednesday....
Sainsbury's has said it will cut up to 2,000 jobs from its human resources staff as part of plans to reduce costs.
The UK's second biggest supermarket chain says the "difficult decision" will affect roles in stores, as well as in the company's central offices.
It plans to make 1,400 payroll and HR clerks redundant and other changes could see another 600 posts removed.
Sainsbury's is looking to save £500m amid fierce competition from discounters and rising food costs.
The majority of the headcount losses will be from within its supermarket stores.
The 600 roles on which the group is consulting are predominantly HR roles across the supermarket chain, its newly acquired Argos chain, as well as Sainsbury's bank.
Sainsbury's also owns Habitat, and employs nearly 200,000 people in total.
It said it would offer affected staff alternative roles wherever possible, or redundancy packages.
Discounts and competition
Sainsbury's said last November it aimed to reduce its running costs by £500m within three years.In March, it said it would cut 400 jobs.
Its biggest rival Tesco is also shrinking its headcount.Earlier this year, Tesco said it would cut 1,200 jobs from its head office, just days after revealing that more than a thousand jobs were going at its Cardiff call centre.
All the big established grocers are juggling rising costs and increased competition from the discounters.
Analysis:Emma Simpson, business correspondent
It's hard to keep pace with the scale of cost cutting and restructuring underway at Britain's biggest grocers.
They're facing a perfect storm of rising costs and changing shopping habits.
And with the competition still cut throat from the discounters, they can't afford to recover those costs by putting up prices too much for the consumer.
Sainsbury's and its other main rivals are all trying to reduce operating costs and simplify their businesses to make them more efficient.It's a big, structural, shift and painful for all those affected.
Figures released earlier on Tuesday by Kantar Worldpanel showed Lidl and Aldi adding sales in the double digits, while established giants were growing sales by around 2%.
Even so, Tesco has 28% of the UK's grocery market, while Sainsbury has just short of 16%.Image copyright Newscast
A Sainsbury's spokesman said the UK grocery market was "changing at a rapid pace" and meant the firm needed to "transform the way we operate".
He said the supermarket was proposing updates to its HR systems and changes to a number of other support roles as part of a consultation.
"This has been a difficult decision and we appreciate that this will be a tough time for those colleagues affected by the changes.We will support them in any way we can," he added....
A Facebook page has been set up to help identify the victims of Somalia's deadliest terror attack in a decade as well as those still missing.
A lorry full of explosives destroyed hotels, government offices and restaurants at a busy junction in the capital, Mogadishu, killing at least 281 people and injuring another 300.
Somali authorities are struggling to identify the dead - leaving relatives helplessly searching for news.
A group of young people have been raising money for relatives and posting pictures of the missing under the Facebook banner, Gurmad252.Gurmad means "Come and help each other" while 252 refers to Somalia's telephone code,Image copyright Gurmad252 Image caption
Photos are accompanied by brief information about where the person was last seen with a number to call should anyone have information.
The team, which has the backing of the government, is also posting the names of those who are being treated in hospital.
It is unlikely we will ever know the identities of everyone who died in the 14 October Mogadishu attack.But this is what we know so far.
Maryam AbdullahiImage copyright Gurmad252
A medical student at Benadir University in Mogadishu, Maryam Abduallahi, 25, was preparing to graduate on Sunday.
Her father, who lives in the UK, had travelled especially to Somalia for her graduation, but ended up attending her funeral.
Maryam's sister Anfa'a Abdullahi Mohamed told the BBC Somali Service that she had tried to reach her sister after the explosion.
"I called her number after the explosion, no-one answered.
"I called back and a young man answered and said, 'Your sister is dead and her body is at Safari Hotel.May Allah have mercy on you.'
"Our family is saddened.My parents are most distressed.May God make their hearts strong," she said.
Her older sister had been a role model who liked helping people at the hospital where she worked and at the university, she added.
"She was planning to start training at a mother and baby clinic after her university graduation.She had ambition."
Fa'iso Hassan Ali:MissingImage copyright Gurmad252
Fa'iso Hassan Ali, 24, had a shop next to Safari Hotel, which was destroyed in the explosion.
Called "Mama Halima", the shop was totally demolished.
Her family have been looking for her since Saturday.
Omar Haji Mohamed's son and daughter:Missing
Omar Haji Mohamed has appealed for information about two of his children, a son and daughter, who are thought to have died in the explosion.Image copyright Gurmad252 Image caption
They were at the family's shop in Soobe, the area where the attack happened, and have not been seen since.
Mr Mohamed has been moving between hospitals and help centres, but has not found them amongst the injured.
Suleiman Nuur Ali:MissingImage copyright Gurmad252
A public transport conductor, Suleiman Nuur Ali, 29, had been at work on Saturday in Soobe.
He has not been seen since the attack.
"Please if you get him dead or injured, contact us," a message from his family says.
Bureeqo Abdullahi Adan:MissingImage copyright Gurmad252
Bureeqo Abdullahi Adan, 17, was known to be travelling on a bus when the blast happened.
Her relatives are asking for any information.
Asad Abdi Abiid:MissingImage copyright Gurmad252
Abdi Abiid was also last seen in Soobe.The area is near Somalia's CID headquarters and foreign ministry.
His family have not heard from him since Saturday.
Fifteen school children:Missing
According to the director of a Mogadishu ambulance service, 15 primary school children were among those who died.
Abdulkadir Adam told the Associated Press news agency that they had been on a school bus when the lorry exploded.
Amid all the sorrow and despair, Gurmad252 has found some good news to share.A young woman who had been reported missing has been found alive....
A widow sobbed as she told a court how she held her dying husband's hand and told him she loved him after he was run over by car thieves.
Mike Samwell, 35, had been woken in the early hours by a break-in at his home in Chorlton, Manchester, in April.
The city's crown court was told he ran out of the house and when his wife followed she found him on his back with tyre marks on his chest.
Ryan Gibbons, who denies murder, is accused of running over him twice.
Mrs Samwell broke down in tears as she gave evidence from behind a screen.Image copyright GMP Image caption
In a police video interview played to the jury, Mrs Samwell said:"When I got to him, he had tyre marks across his chest.
"There was blood coming out of the back of his head.He was making an awful noise.
"I was ringing the police and trying to talk to the police.
"I was shouting 'Help!Help!Somebody help me!'.
"I was just telling him that I loved him and holding his hand."
Alistair Webster QC, prosecuting, told the court:"One of the rear wheels was actually on Mr Samwell's chest.He was screaming."
Mr Webster said 29-year-old Mr Gibbons, despite his denial and claims he only felt a "bump", must have known he had driven over Mr Samwell.
He said that audio captured by a CCTV camera near the scene recorded "a yelp, a shriek, a large crash, a small crash.Female screams, harsh engine acceleration and shouts for help".
The court heard Mr Samwell, a nuclear engineer, suffered 39 separate external injuries, with "catastrophic" damage to his chest and heart.
Mr Gibbons, of Steven Court, Chorlton, admits burglary and aggravated vehicle taking without consent, but denies murder and manslaughter.
Co-accused Raymond Davies, 21, of Castlefield Walk, Manchester, also admitted a count of burglary but denies manslaughter and aggravated vehicle taking without consent.
He is alleged to have transported Mr Gibbons to the scene of the crime and helped him escape afterwards.
The jury was told police believe two other men were involved in the burglary but have never been traced.
Stacey Hughes, 28, of Steven Court, Chorlton, is also on trial and denies a charge of assisting an offender.
The trial continues....