ST. AUGUSTINE, Fla. – The Castillo De San Marcos in St. Augustine was evacuated midday Wednesday as authorities responded to an unannounced surveillance exercise.
The fort reopened after about 30 minutes, according to St. Augustine police.
Police said an instructor from a security business in DeLand brought four students -- two of whom are Middle Eastern -- to the Castillo to do surveillance and counter-surveillance exercises. The instructor did not tell police or the U.S. Park Service.
The St. Johns County Sheriff's Office Bomb Squad and bomb-sniffing K9s were also deployed, and streets around the Castillo were closed during the evacuation.
Police are talking to the instructor now, and telling him the expense that was involved in responding to the possible threat.
Police said the fort was cleared as a precaution.
The police were notified of the activity within minutes of President Barack Obama calling for Americans to be vigilant.
"As Americans travel this weekend to be with their loved ones, I want them to know that our counterterrorism, intelligence, homeland security and law enforcement professionals at every level are working overtime," Obama said.