This is what we know so far:
NewsLondon terror attack - what we know so farBy The NewsroomPublished 23rd Mar 2017, 12:00 BSTUpdated 24th Mar 2017, 10:09 BST Police officers conduct a fingertip search on Parliament Square. PIC: PAA massive police operation is under way after a terror attack in Westminster, in the heart of London.This is what we know so far:Related topics:London