New Delhi, July 4 -- By the time the largest explosions rolled across the capital around two in the morning on Thursday, some 52,500 people were already underground, spread across the city's metro platforms with blankets, phones and children who had learned to sleep through air raid sirens. What they surfaced to was a changed city: an ambulance station hit, a hotel burning, a publishing warehouse with roughly 800,000 books reduced to ash, and a nine-story apartment block that no longer existed.

by Friday, officials put it at no fewer than 30 dead and more than 85 injured, with several people still missing, among them the parents of a 10-year-old boy pulled from the rubble. Mayor Vitali Klitschko declared Friday a day of mourning.

Presid...