Armed police arrested four people during raids at a series of homes in the UK to foil a planned Islamist terrorism plot. Two men, aged 27 and 31, and a 17-year-old boy were arrested in London while another man, 32, was held in Leicestershire, central England, according to police. Raids at the two homes in north-east London on Thursday were captured on camera by onlookers. The footage showed a group of about eight officers at the doorway of the semi-detached home ordering a man to put his hands on his head before he was pulled out of the house and led away. Another video showed officers near a block of flats. Police said that the 27-year-old suspect was bitten on the foot by a police dog during the operation and was taken to hospital. His injuries were not serious. The four have been detained on suspicion of preparing terrorist attacks and were held in custody while officers searched four properties. Police said the raids were part of an investigation into a possible Islamist terrorist plot. The UK’s security services currently rate the threat of terrorism as ‘substantial’, suggesting that an attack is likely. Three people died in a park in Reading, west of London, on June 20 in what was described by police as a terrorist attack. A man, Khairi Saadallah, has been charged with three counts of murder. British police have issued warnings that the Covid-19 lockdown has hampered deradicalisation efforts and extremists could be using the opportunity to exploit vulnerable youngsters spending more time online.