Now, as the country tries to return to normal life, Indians are asking why their government was not able to stop the attacks. In response, two top government officials have resigned.
Long-running tensions between India and Pakistan also have been stoked in the wake of the attacks. An investigation is underway to determine whether the 10 known gunmen had links to Pakistan.
So what does this mean for the security of India and for its already tenuous relationship with Pakistan? How might life in India's financial capital of Mumbai change? What are people who live in the city saying about the attacks?
Special correspondent Simon Marks, who is reporting from Mumbai, answered your questions in a special video dispatch.