Authorities have released video and close-up images of two young men carrying backpacks that are being sought for questioning in the Boston Marathon Bombings. FBI sources will only identify them as 'Suspect 1' and 'Suspect 2'.

The time-lapse images, taken from security equipment show both suspects walking through the crowd near Boylston Street moments before the attacks.

FBI Special Agent Richard DesLauriers said in a press conference,earlier today (Thursday):

"These images should be the only ones that the public should use to assist us. Suspect 1 is wearing a dark hat, Suspect 2 is wearing a white hat. Suspect 2 dropped a backpack at the site of the second explosion."

If you have any information on the bombings or can identify these two people of interest, contact the FBI: http://bostonmarathontips.fbi.gov/