The header comes from a photo that shows spectators helping victims soon after the Boston Marathon bombs exploded. The photo comes from https://commons.wikimedia.org/wiki/File:1st_Boston_Marathon_blast_seen_from_2nd_floor_and_a_half_block_away.jpg. It was taken by Aaron Tang and is licensed under the Creative Commons Attribution 2.0 Generic license.
About the Second Image
By UpstateNYer - Own work. For more details see https://en.wikipedia.org /wiki/September_11_attacks#/media/File:September_11_Photo_Montage.jpg.