BARCELONA, Spain — Police on Monday shot and killed the man believed to have driven the van that mowed down pedestrians along the famed Las Ramblas promenade here last week, bringing an end to a high-stakes dragnet that had put the nation on edge.But even as Catalonians and Spaniards breathed a sigh of relief, some feared that an upcoming Catalonian independence referendum slated for Oct. 1 would worsen divisions between central government officials in Madrid and Catalan authorities who traditionally have resisted working together.
