More officers will be stationed at transport hubs around the capital this weekend.
The 19-year-old man was arrested after police received reports of a clown brandishing a chainsaw
Their family fears they were killed in a case of mistaken identity.
'A spit hood can be deeply distressing and humiliating'.
About Metropolitan Police
The Metropolitan Police Service was founded by Sir Robert Peel in 1829. Today its head is commissioner Cressida Dick. The Met police has recently been subject to controversy over allegations some journalists gave money to police for information during the phone hacking scandal. A force is also known as "the Met", "Met Pol", "MP" and "the MPS" and has more than 31,000 officers together with about 13,000 police staff and 3,700 Police Community Support Officers (PCSOs). The MPS is also being supported by 2,500 volunteer police cadets and more than 5,000 volunteer police officers from the Metropolitan Special Constabulary (MSC) and its Employer Supported Policing (ESP) programme. The Metropolitan Police Services covers an area of 620 square miles and a population of 7.2 million.