Two dozen American flags of varying size now wave at the site where a bomb exploded last weekend in Seaside Park.
People have been driving by to admire the makeshift tribute and take pictures. Some have added their own flags to the display.
A small wooden cross is also in the sand, along with two Marine Corps flags.
The bomb was allegedly intended to injure runners and spectators at a Marine Corps charity race. Last-minute registrations and a large crowd contributed to a late start for the race, which saved lives.
Residents near the memorial say FBI agents were back in the area late Wednesday afternoon, combing the beach and dunes for more possible evidence.