A Chinese graduate student from Boston University has been confirmed as one of the three killed during the blasts at Monday's Boston Marathon.

The Chinese Consulate in New York confirmed the death of the Chinese student on its website on Tuesday. A consulate press officer said they are not releasing the student's identity at the request of the victim's family.

Boston University newspaper BU Today reported that a graduate student from the university was among the fatalities of the bombings, which also injured more than 170.

Meanwhile, Chinese President Xi Jinping has sent his condolences to President Barack Obama over the tragedy. In his message, Xi expressed his deep sympathy and sincere condolences to the US government and its people over the losses and casualties caused by the bombings.

Zhou Danling, a female Chinese graduate student from Boston University, was injured during the blasts at the Monday Marathon. Zhou, from Chengdu, is being treated at the Boston Medical Center and is said to be in a stable condition.

Together with Zhou when the explosions happened near the marathon finish line on Boylston Street at about 2:50 pm were her two university friends Qian Tingting and Lu Lingzi. Qian was unharmed, but Lu has been reported as missing.

"Zhou had abdominal injuries from the blast. She came out of the coma today and is in a stable condition now," said Owen Zhang, 21, from Shenzhen, who is studying at Boston University.

"I got Zhou's parents' permission to post that message and it helped spread the word so her family and friends know her condition," said Zhang, adding Zhou's parents are trying to get the visa to the US to visit their daughter.

Zhang, who has lived in Boston for two years, said if he didn't oversleep on Monday, he would probably have been on the same block where Zhou and her two female Chinese friends were when the blast happened.

"Zhou and her friends were not there to watch the marathon actually," said Zhang. "They were there for an appointment with the Apple store to fix an iPhone."

Robert Hill, dean of Boston University's Marsh Chapel, who visited Zhou in hospital, said that she had undergone surgery on Monday and on Tuesday.

"She is doing well," Hill told BU Today. "She has her friends around her, and she will soon have family around her."

Some 27,000 runners from nearly 70 countries competed in the marathon. China's real estate developer Vanke had a team of 15 runners in the event. All were reported to be safe.

"It was very disturbing to witness, but I was very moved to see how people helped one another in the chaos," said Vanke Chairman Wang Shi, who was across the street in the VIP box watching the race when the explosions happened. "No matter who is behind this, Boston and American people won't be defeated by the evil."

Luis Vasquez, 25, a Boston resident who was just leaving home to watch the marathon when the explosions happened said it was so "unrealistic".

"I don't know what it was - I think we were just lucky with that timing, one of those fortunate ones, you know," he said.

Hu Haidan and Derek Bosko contributed to the story.