There are still many unanswered questions after yesterday's series of bombings in Mumbai, which killed at least 17 people and injured more than 130. Investigators don't know yet who is responsible, or what their motivation was. What they do know is that bombs went off at rush hour in three different sites – in the Opera House district, near the Zaveri Bazaar, and near a transport hub in a suburb – and city residents want to know why, after 2008's deadly attack, something like this was able to happen.