Three separate explosions tore through a business district in India’s Mumbai Wednesday, leaving at least 17 people dead and 141 injured, authorities said. Less than an hour after the series of blasts, its Home Ministry confirmed a terrorist attack and placed the entire city on high alert.

Although no group claimed responsibility, the explosions hit locations where a terror siege nearly three years ago killed 166 people. Wednesday also coincided with the birthday of the lone surviving gunman of the 2008 attack.

Arup Patnaik, a top police officer, said the attackers used improvised explosive devices in the attack, hidden in an umbrella in the Jhaveri Bazaar jewelry market and kept in a car in the business district of Opera House.

Indian officials say they believe the responsibility of Wednesday's attack rests with the Indian Mujahideen, a group that works closely with Lashkar-e-Taiba.

Lashkar-e-Taiba is the group suspected to be behind the 2008 attack. 

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All three blasts happened from 6:50 p.m. to 7 p.m., when all the neighborhoods would have been packed with office workers and commuters.

The blasts hit the crowded Dadar neighborhood at rush hour, the famed jewelry market Jhaveri Bazaar and the busy business district of Opera House, an official at the city's Police Control Room said. The official spoke on condition of anonymity because of office policy.

The explosions happened around 7 p.m., when all the neighborhoods would have been packed with office workers and commuters.

Authorities say an early indicator of a terror strike was the close timing of the string of explosions.

President Obama and Secretary of State Clinton condemned the attack in a statement and said the U.S. is monitoring the situation.

The 2008 attack, which targeted two luxury hotels, a Jewish center and a busy train station, was blamed on Pakistan-based militant groups. The attacks escalated tensions between the nuclear-armed rivals and prompted them to suspend peace talks.

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

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.

The Associated Press contributed to this report.