Maybe it had something to do with the human right movement, the demonstrations in this town, fighting for racial integration or KKK activity.
Full text of "Racial and civil disorders in St. Augustine: report of the Legislative Investigation Committee"
A very small part of this very long, but very interesting read.
The Battle of the Beaches
The battle now shifted to the world famed St. Augustine
beaches, several miles east of the city proper. Here again
violent clashes between negroes seeking to integrate the
beaches and whites opposing them supplied "made to order"
footage for the TV and news camera. The fact that camera-
men always arrived on the scene well ahead of the "non-
violent" demonstrators more or less gave away the whole
show as a planned and stage-managed propaganda produc-
tion for nationwide consumption. At one point, when they
found their way into the surf barred by segretationists, the
demonstrators kneeled on the wet beach to conduct prayers.
State officers were vigorous in using their clubs on the heads
of the white counter-demonstrators. Several were severely
beaten on the head and required hospital attention.
Peace and quiet prevailed in the old city for a few days
but on July 4, 1964, some 200 robed Klansmen arrived to
stage a provocative parade. The racial truce was further
marred by a gang of white toughs attacking six Negroes
fishing from a bridge. The police later arrested nine of them
and charged them with assault and battery.