london - The attack in London was committed with a improvised bomb which was only halfway off. That's what police spokesman Mark Rowley says.
It is a so-called 'improvised explosive device', a nice term used by the police for an explosive explosive.
Video was indeed an explosive, in a white bucket, with a plastic LIDL bag around it. Flames came from the bucket. Whether the police mean the bucket is not made clear, but that is very plausible.
The police also confirm to the British newspaper The Guardian that the homemade bomb has not gone completely. That has concluded experts who have seen the explosive. The news suggests that the attack, in which no dead have fallen, could have been worse.