"Several officials have been dispatched from our foreign mission in New York to provide aid and support to South Africans who may have been caught up in the tragedy that has unfolded in Boston," Clayson Monyela, spokesperson for the department of international relations and co-operation said on Tuesday.
At least three people were killed and more than 100 were injured in twin explosions near the finish line of the Boston Marathon on Monday, while the race was in progress.
Twenty-five South Africans took part in the race and two were injured in the blasts.
"Our information is that they are being treated for minor injuries and will receive further aid from our consular staff we have dispatched there," Monyela added.
The international relations department could not provide the identities of the South Africans injured.
Jumping to conclusions
Meanwhile, US President Barack Obama vowed justice for the victims of the bomb but cautioned against the urge to "jump to conclusions" before a full investigation is done.
"We still do not know who did this or why, and people shouldn't jump to conclusions before we have all the facts," Obama told reporters at the White House.
"But make no mistake, we will get to the bottom of this. We will find out who did this, we will find out why they did this. Any responsible individuals, any responsible groups, will feel the full weight of justice."
As of Tuesday morning, no organisation had accepted responsibility for the attack nor had the FBI or any other US agency found any evidence pointing to the perpetrators.
The Federal Bureau of Investigation (FBI) is heading the investigation with help from Boston city and Massachusetts state officials.
"It is a criminal investigation that is a potential terrorist investigation," FBI Special Agent Richard DesLauriers said at an evening news conference.
He declined to elaborate on initial findings or where the probe was headed.
Assistance to SA citizens
Monyela said all South Africans assisted by consular officials will receive help on their own terms.
"We never take decisions on behalf of South Africans. Those who want to return to South Africa will be assisted in doing so and those who would prefer to remain in the USA will be assisted in that regard," he added.
South African wheelchair athlete Ernst van Dyk took part in the race and witnessed a man having both his legs blown off in the blasts.
"It was terrible," Van Dyk said during a radio interview with 94.7 Highveld Stereo on Tuesday morning.
He was at a post-race celebration with some of his sponsors at a hotel overlooking the last stretch of the race when the explosions happened.
"Initially, we heard the first explosion … nobody was sure what it was. I thought it was like maybe premature fireworks or something and everyone went to the window," Van Dyk added.
Oldest marathon in the world
Van Dyk said he could not imagine who could be behind the blasts.
"It's the oldest marathon in the world. It's got so much history and you have to ask yourself who would be so sick."
Monyela offered condolences to those affected by the attack on behalf of the South African government.
"We can only hope the perpetrators of this most foul deed will be brought to justice," he added. – Additional reporting by Sapa