Conversation so far:
where did the boston bombers live in cambridge
The Tsarnaev brothers lived on Norfolk Street in Cambridge, Massachusetts.
where are the tsarnaev brothers now
Tamerlan Tsarnaev died from gunshots. Dzhokhar Tsarnaev is on death-row at ADX Florence prison.
why did the tsarnaev brothers bomb boston
During questioning, Dzhokhar said that he and his brother were motivated by extremist Islamist beliefs and the wars in Iraq and Afghanistan.

Question: how many people died in the bombing
Self-contained rewrite: how many people died in the boston marathon bombing