Sounds like an attack by the likes of Sheik Rachman and his followers... the ones who tried to bomb the holland tunnel, FBI building and UN a while back. It could also be the followers of that one eyed, no armed cleric that was arrested in London a few weeks back, who is awaiting extradition to the US. He had staged a march through Traglafar Sq. a few months ago, and his followers had expressed intent to attack 'the western powers' since his arrest.
Or- it could just be the IRA acting up again.