LONDON (Reuters) - British police said on Friday that they were treating as a  terrorist incident  reports of a blast at a west London metro station.  Armed police rushed to reports of a fire on a train at a London underground station with local media reporting there had been an explosion on a packed rush-hour commuter train.  Deputy Assistant Commissioner Neil Basu, the senior national coordinator for CT policing, has declared it a terrorist incident,  the Metropolitan Police said in a statement on Friday.  