A knife with an 8cm blade was one of three dangerous weapons taken off the streets in Hounslow.
A large curved knife with a sharp pointed blade, a smaller rounded edge knife, and a third with a jagged edge were seized.
Officers carried out a stop and search of a group of teenagers after a call from a concerned member of the public said young people were smoking cannabis in the area.
Hounslow police were called to the scene at around midday on October 31.
Three male teenagers aged between 16 and 17 were arrested and have been charged with points and blades in a public place and possession of an article with a blade on school premises.
The teenagers, two aged 16 and one aged 17, are due to appear at Ealing Magistrates Court on November 15.
Anyone who knows people who carry a knife or wants to report any knife crime, call police on 101 or contact Crimestoppers anonymously on 0800 555 111.
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