Dr. Manmohan Singh, Prime Minister of India, on Tuesday condemned the deadly attack at the Boston Marathon that left three people dead, including an eight-year-old boy, and injured more than hundred people.

"I am deeply shocked and saddened by the outrageous terrorist attack in Boston yesterday. This senseless and cowardly act of violence has struck a city that has long stood as the symbol of openness, learning, innovation and enterprise," said the PM in a message to United States President Barack Obama.

"The people of India join me in condemning the attack in the strongest terms. We stand in solidarity and sympathy with the bereaved families, the injured and the people of the United States."

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Runners continue to run towards the finish line as an explosion erupts at the finish line of the Boston MarathonReuters

The PM also expressed his solidarity with the American people in the struggle against terrorism saying, "we offer you our full support for the investigations into the attack."

Twin blasts left a gruesome scene at the Boston Marathon even as the participants were about to reach the finishing line.

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Bystanders tend to an injured man following explosions at the Boston Marathon finish areaReuters

Three people, including an eight-year-old boy, were killed by the blasts and over 150 people were injured. Some of them were said to be critically injured.

The first blast, which blew out the window of a store near the end of the race course at around 2:50 p.m.(1850 GMT), stunned the throng of people who had gathered in Copley Square for the race's finale. A few seconds later, a second blast sent waves of fear and horror through the crowd, according to Reuters.

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NBC still image taken from video shows an explosion at the Boston MarathonReuters

"I saw multiple injuries. I saw people who looked like they had their legs blown off. There was a lot of blood over their legs," Reuters quoted Anderson, a 33-year-old fisherman from Pembroke, Massachusetts, as saying.

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An injured woman is attended to at the scene of an explosion at the Boston MarathonReuters

The FBI Boston Division has asked the public to give information that could give clue on the attackers.

The officials have no clue on the motive of the attack and the suspects.

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NBC still image taken from video shows an explosion at the Boston MarathonReuters

(With Inputs from Reuters)