World leaders are condemning the deadly bombings at the annual Boston Marathon in Massachusetts.
UN Secretary-General Ban Ki-moon called the twin explosions at the race's finish line “all the more appalling for taking place at an event renowned for bringing people together from around the world.”
Russian President Vladimir Putin denounced the “barbaric crime” and offered Russia’s assistance.
Afghan President Hamid Karzai said his country feels “the pain and suffering arising from such incidents.”
The attack killed three people and wounded more than 100 others.
No suspects are in custody, and there has been no claim of responsibility.
U.S. investigators led by the FBI are examining video footage taken by spectators as part of the hunt for who carried out the double bombing.
President Barack Obama did not describe the April 15 blasts as "terrorism," saying the investigation continues.
PHOTO GALLERY: Boston Marathon blasts kill three, injure more than 140
In a brief statement to reporters at the White House, Obama pledged to find the perpetrators and bring the "full weight of justice” against them.
“We’re still in the investigation stage at this point, but I just want to reiterate: We will find out who did this and we will hold them accountable," Obama said.
Obama said he had ordered that the full resources of the federal government be made available to aid victims and assist in the investigation.
The Federal Aviation Administration imposed a no-fly zone over the site of the explosions, while security was increased in New York City, Washington, Los Angeles, San Francisco, and other cities in response to the Boston bombs.
Some reports said at least one unexploded suspected device had been found in Boston and was dismantled by experts.
Some 23,000 runners from dozens of countries took part in the 42-kilometer race, which is considered the world’s oldest annual marathon.
With additional reporting by Interfax and dpa