The spectacular scene unfolded about 7 p.m. on the north section of the four-lane Interstate 5 bridge near Mount Vernon, about 60 miles north of Seattle and 40 miles south of the Canada border.
"Don't say we can't laugh at ourselves, " says a local p.r. executive as she wipes tears from her eyes during a scene that could best be described as toilet humor encountering adolescent high spirits.
The video and photos provided by federal prosecutors showed the two brothers carrying backpacks as they walk onto Boylston Street, the scene of the bombings, about 11 minutes before the first blast occurred at 2:49 p.m.