Anti-knife crime protesters smeared themselves with fake blood outside YouTube's London offices in protest at the Google company's alleged promotion of graphic content.
Britain has very tough gun laws and shootings across the country are relatively rare.
But knife crime has been a problem for much of the past decade -- particularly in poorer neighbourhoods of big cities such as London where gang violence remains a concern.
Activists have appealed to social media platforms, expressing concern at the amount of crime-related content.
YouTube ‘is a contributing factor,’ Elaine Donnellon, lead organiser for the Operation Shutdown campaign group, told AFP at a rally with around 20 other women.
‘They have blood on their hands.’
Official statistics show 285 people were stabbed to death across England and Wales between April 2017 and March 2018.
The figure is the highest for a 12-month period since such records began being compiled in 1946.
Campaigners said they had unsuccessfully tried getting YouTube to take down music and other videos taunting and mocking people who had their relatives and children murdered.
‘We flag video all the time and we're very lucky if they get taken down,’ said group member Sarah Hutchings, who lost her cousin to knife crime.
YouTube says its UK policy is to block videos in which people brandish weapons in a threatening manner.
A spokesman for the internet giant said it was working with the London police and mayor's office ‘to take action on gang-related content that infringe our community guidelines or break the law’.
‘Along with others in the UK, we share the deep concern about this issue and do not want our platform used to incite violence,’ the YouTube spokesman said.
- Drill music -
Operation Shutdown members said they were particularly concerned about drill music -- a British hiphop style that often glamourises knife crime and gang life.
Some welfare campaigners call this focus misguided.
They point to broader problems that affect big cities with a large divide between richer white-upper class neighbourhoods and multiracial working-class ones.
But campaigner Lucy Martindale said YouTube has helped spread drill music to the masses in the past decade with the emergence of the now-ubiquitous mobile phones.
‘When I was growing up we did not have YouTube,’ said 29-year-old Martindale, who said more than 10 of her family and friends had been murdered.
‘There was drill music but not to the extent (there) is today. So it definitely helped the increase of violence,’ the protester said.
‘By using YouTube and the internet, anyone can access it. All you need is a phone.’