The U.S. Federal Bureau of Investigation (FBI) and other investigative authorities have asked for the publics help to identify two men suspected of carrying out the Boston Marathon bombings.

Investigators released video and video stills of two male suspects on Thursday who were on site right before the explosion killed three and maimed dozens of bystanders on Monday.

The Federal Bureau of Investigation's special agent in Boston Richard DesLauriers said the video was captured by a security camera around the finish line of the marathon where the blast occurred.

U.S. President Barack Obama traveled to Boston on Thursday for a memorial service for the victims and vowed to find the perpetrators and bring them to justice.