The arrests come after a series of posts on Snapchat and TikTok urged students as young as 11 to get hold of weapons and get ready for “war”.

As part of the viral phenomenon, different schools were divided into ‘team red’ and ‘team blue’, in reference to the infamous US gangs, Crips and Bloods, who wear the colours as uniform.

The suspects – a 15-year-old boy and a man in his 20s – were arrested by the Metropolitan Police on suspicion of encouraging or assisting in a crime and have been bailed while the investigation continues.

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The Met has also called on social media platforms to take down the posts and have told pupils to ignore the instructions and not wear the colours associated with the craze.

One parent, Annette Quinn, told LBC: “I’m really worried about my two sons. They’re terrified to go to school. There is a fight arranged for Monday in Croydon and he’s asked if he can stay at home.

“It just takes one kid to take it seriously and be an idiot. Schoolchildren- especially boys – are full of bravado anyway, but there’s so much pressure on kids today to be the biggest, the toughest.

“Intra-school rivalry has always been an issue. And the fear is that the kids don’t need much encouragement to take it a step further.”

LBC understands several parents have sought permission for their children to not attend school until their safety can be guaranteed.

The force has written to worried parents amid safety concerns.

One letter said: “Dear parent/carer, we are aware that several posts have been circulating on social media in recent days, and we understand that this may have caused concern among families.

“The Metropolitan Police are monitoring the situation closely and are in regular contact with schools across several London boroughs to offer reassurance and support.

“Police officers will continue to maintain a strong and visible presence around schools, where appropriate. They will respond promptly and firmly to any reports of violence or disorder to help ensure the safety of all young people

“The police are also monitoring online activity and have worked with social media platforms to request the disabling of several accounts where threats or encouragement of violence were identified.”

The posts urge pupils to “tool up” and “bring your sharpest bledez” in a series of arranged mass fights between schools.

A police source said that the arranged fights did not happen, but officers are continually monitoring social media.

LBC understands both TikTok and Snapchat have taken down several posts and are continuing to monitor their platforms for the posts.

A Metropolitan Police spokesperson said: “On Sunday, 1 March at approximately 18:45hrs, Met officers arrested two individuals in Central East London in connection with a recent trend of social media posts.

“Both suspects, a man aged in his 20s and a boy aged 15, were arrested on suspicion of encouraging or assisting in a crime. They were bailed pending further enquiries.

“A strong police presence remains around schools, particularly at the end of the school day.

“Local officers continue to work alongside local authority partners, school leaders and parents, whose joint robust response has been vital in protecting young people across the last week.”