US President Barack Obama has directed his administration to provide whatever assistance necessary in the investigation and response to the deadly Boston Marathon explosions on Monday afternoon.

"The President has been notified of the incident in Boston," said the White House pool report, quoting an unnamed White House official. "His administration is in contact with state and local authorities."

"He directed his administration to provide whatever assistance is necessary in the investigation and response," said the White House pool report.

Two explosions went off on Monday afternoon near the Boston Marathon finish line. According to latest report by CNN, at least two have been killed, with another 28 injured, in the explosions.

So far, it is still not clear if the explosions are terrorist attacks. A news conference by local authorities is expected soon.