LONDON — A lone attacker mowed down pedestrians and then stabbed a policeman in the shadow of the British Parliament Wednesday, in what police described as a terrorist strike that left the attacker and at least four others dead and some 40 people injured on nearby Westminster Bridge.Metropolitan Police Assistant Commissioner Mark Rowley told reporters that police officer Keith Palmer, 49, three civilians and the attacker had died in the brief but intense incident, which again dramatized the threat terrorism poses to the great cities of Europe.
