MUMBAI: Three near-simultaneous explosions rocked Mumbai at rush-hour on Wednesday, killing at least 21 people and injuring 141 in what the government said appeared to be another terrorist strike in the city hit by a major attack nearly three years ago.

Maharashtra chief minister Prithviraj Chavan said the latest attack killed 20 people, and home minister P Chidambaram said the toll was likely to rise.

Television footage showed dozens of police officials, several of them armed, at the sites of the explosion and at least one car with its windows shattered. A photograph showed victims of a blast at the Zaveri Bazaar crowding into the back of a cargo truck to be taken to a hospital.

Because of the close timing of the string of explosions, ``we infer that this was a coordinated attack by terrorists,'' home minister Palaniappan 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 2008 attack killed 166 people and was blamed on Pakistan-based militant groups. Tensions escalated between the countries and peace talks were suspended. The talks recently resumed.

Soon after Wednesday's blasts were reported, Pakistan's government expressed distress on the loss of lives and injuries.

The blasts would 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 Jewish center and a busy train station. 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.

