Detectives investigating last week's terrorist attack on a Tube train in London have arrested a 17-year-old boy in Thornton Heath in south London.
Six people are now being held for questioning about the attack in which 30 people were injured when a homemade bomb partially exploded on a rush hour train at Parsons Green.
Officers have also carried out a search of the property where the teenager was arrested.
Commander Dean Haydon, head of the Metropolitan Police Counter Terrorism Command, said: "This continues to be a fast-moving investigation. A significant amount of activity has taken place since the attack on Friday.
"We now have six males in custody and searches are continuing at five addresses. Detectives are carrying out extensive inquiries to determine the full facts behind the attack."
The investigation into the rush hour bombing has seen three men aged 25, 30 and 48, detained in Newport, south Wales, a 21-year-old named Yahyah Farroukh arrested in Hounslow, west London, and an 18-year-old man detained at the Port of Dover.
A time limit on Mr Farroukh's detention is expected to expire today, while detectives have been given until Saturday to continue questioning the 18-year-old suspect.