A box truck explosion in Port St. Lucie and moments later in Stuart, there's a fire at Witham Field, and a suspicious backpack found.
At Harbor Branch Oceanographic Institute, terrorists move into the inlet, where they're met by a law enforcement helicopter.
This is only a drill. On Wednesday, "Operation Troubled Waters" brought together 34 local, state, and federal agencies in this mock-terrorism exercise.
As agencies lock into their roles, observers are watching, and taking notes.
"Testing and evaluating our ability to respond to a potential terrorist or unknown type of incident," says Bureau Chief Chris Stabile with Martin County Fire-Rescue.
Tried and true techniques are used along with new technology.
The Martin County Sheriff's bomb robot was deployed to see if there's an explosive in the suspicious backpack.
There were three main exercise locations and four hospitals receiving the "patients."
For some of those playing patients, more respect for those who are called upon in an emergency.
"We depend on these people to save our lives. The more real we can make it, the more their adrenaline and their anxiousness to help has to go up," said Pat Ayres.
Nursing students from Jensen Beach High School played the injured at Witham Field.
"It was interesting to see how they did all the chemical attack things and see what they do in real life and what they would do in a disaster scenario," said Senior Savannah Mier.
Scripps Only Content 2017