Plot Could Still Be Underway

British officials warn that an attack could still be underway as they continue their search for more suspects.

Scotland Yard officials do not believe they have captured all the members involved in today's terror plot out of Heathrow Airport and are urgently searching for more suspects.

Authorities are concerned that those still at large may well have instructions to act now if the plot was disrupted, and they have not ruled out other cities and airports as possible targets of attacks. ABC News has been told that this is a well organized, "for real"  plot, not an informant's suggestion.

The Blotter continues to provide excellent coverage of the developing story.