Three near-simultaenous blasts rocked the city of Mumbai in India during rush hour on Wednesday in what the government believes is a terror attack.

A National Investigations Agency team was en route to to Mumbai, the world's fifth most populous city and home to 20.6 million people, within minutes of the attack.

Maharashtra chief minister Prithviraj Chavan said the latest attack killed 20 people and wounded at least 100, but home minister PalaniappanChidambaram warned the toll was likely to rise. 

Because of the close timing of the string of explosions ``we infer that this was a coordinated attack by terrorists,'' Chidambaram said. 
One blast hit the crowded neighborhood of Dadar in central Mumbai. The others were at the Zaveri Bazaar, which is a famed jewelry market, and the busy business district of Opera House, both in southern Mumbai and several miles (kilometers) apart, police said. 
All three blasts happened from 6:50pm. to 7pm., when all the neighborhoods would have been packed with office workers and commuters. 
The blasts mark the first major attack on Mumbai since the November 2008 violence, when 10 terrorists laid siege to the city for 60 hours, targeting two luxury hotels, a busy train station, and the city's Chabad House. There was no immediate indication that Wednesday's blasts were part of a prolonged siege. 
Mumbai has been on edge since then. In December, authorities deployed extra police on city streets after receiving intelligence that a Pakistan-based militant group was planning an attack over New Year's weekend. Police conducted house-to-house searches in some neighborhoods for four men who authorities believe entered the city to carry out a terrorist attack, and computer-aided photographs of the four suspects were released. 
In March 2010, Mumbai police said they prevented a major terrorist strike after they arrested two Indian men, who, police said, were preparing to hit several targets in the city. Then in September, police issued a terror alert for the city during a popular Hindu festival.