Reports from the scene indicate the bombs were each placed in taxi cabs. One went off near the popular tourist site the Gateway of India monument. Minutes later, the second exploded near a crowded jewelry marketplace iin Zaveri Bazaar.
US Secretary of State Colin Powell condemned the blasts. He telephoned India's Minister of External Affairs, Yashwant Sinha, to express his outrage at the attack and offer condolences.
There has been no claim of responsibility. In the past, India has blamed such incidents on Pakistan-backed Islamic militants. Islamabad quickly condemned the deadly bombings as an act of terror.
India's Deputy Prime Minister Lal Krishna Advani said the banned Students Islamic Movement of India and Lashkar-e-Taiba could be behind the bombings.