The UK's top police officer has blamed social media for normalising violence and leading more children to commit stabbings and murders.
Met Police commissioner Cressida Dick told the Times social media sites "rev people up" and make street violence "more likely".
Fatal stabbings in England and Wales are at their highest levels since 2011.
Ms Dick announced a new task force of about 100 officers to tackle violent crime in London.
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Ms Dick says she believes social media "makes it harder for people to cool down", adding: "I'm sure it does rev people up."
"There's definitely something about the impact of social media in terms of people being able to go from slightly angry with each other to 'fight' very quickly," she said.
A trivial disagreement could escalate into violence "within minutes", Ms Dick added, with disputes on sites such as YouTube identified by detectives as partly to blame.
Linking the "incredibly abusive" language online to street violence, she said: "I think it certainly makes it more likely, it makes it faster... it allows a conversation of a 'show off' sort that involves violence."
Ms Dick also told the paper that gangs who post on social media or share videos provoking rivals can glamorise violence.
She said stop and search is "likely to go on going up", adding: "We will be out on the streets more."
Knife crime offences in England and Wales rose by 21% in the year ending September 2017, compared to the previous 12 months, figures show.
Police in London - which sees more knife crime than anywhere else in the UK - have launched 10 murder investigations since 17 March.
On Friday, a woman, 36, became the 10th victim after being stabbed to death in Haringey, north London.
In September last year, the MP for Croydon Central, Sarah Jones, said social media was "fuelling an escalation in the cycle of violence among young people".
She called for ministers to crack down on online material promoting knife crime, naming YouTube, Snapchat and Instagram as problem sites.
Meanwhile, the government has launched a £1.35m series of adverts to run across social media in a bid to deter 10 to 21-year-olds from knife crime.
The adverts feature true stories of teenagers who have been stabbed.