They knew exactly where they lived, who they visited, where they shopped and where they ate dinner, and when.
How?
The cabbies had provided the data on their every move for years in advance.
Soooo, where do most of the cabbies in your berg come from? In Washington DC, it's Somalia...
Just because we've forgotten the lessons of Huế and the lessons of the Sepoy Rebellion's "The Perfect Day" (scrubbed from Wiki, by the way) doesn't mean our enemies have.
Not a lot of taxi service in my burg, York PA. Most people drive themselves.