Once again London has been the subject of a terror attack, this time on the underground, which represents a nightmare scenario for the security services with bombers targeting large number of people in a confined space.
However, the improvised explosive device left on a Tube train yesterday failed to fully detonate, resulting in 22 people needing hospital treatment but thankfully no one died in this despicable act which could have resulted in unimaginable carnage.
Witnesses told of fear and panic after the device, which was left in a bucket inside a shopping bag, partially exploded in a District line carriage at Parsons Green station during the morning rush hour - a time when the train would have been packed with commuters.
The blast caused what has been described as a `fireball', causing burns to those in the immediate vicinity. Among the injured was a ten-year-old boy.
Metropolitan police immediately launched a hunt for the bomber although Theresa May was clearly dismayed when Donald Trump sent out a tweet suggesting the terrorists were known to security services.
Pictures of the device show it to be fairly crude in construction but the police will be hoping the remains of the bomb will yield vital forensic information.
Security experts are also pointing to the broad range of methods being used by fanatical groups and individuals, which in recent months has included attacks involved knives, vehicles and a nail bomb in the case of the Manchester Arena blast.
The use of weapons which are relatively unsophisticated and easy to source is a problem for the police, with jihadists able to formulate their plans without necessarily raising suspicion.
This latest attack will underline the severe threat that continues to exist from the IS-supporting extremists and shows that both the police and public must maintain a high level of vigilance at all times.
