U.S. Navy bases across the country, including Naval Air Station North Island in Coronado, underwent dramatic active shooter drills on Wednesday.
At NAS North Island, an explosion and the sound of gunshots were heard coming from the very spot sailors are supposed to be safe.
The drills were part of a security exercise called Solid Curtain.
As part of the training, some personnel played victims, but Naval Security Instructor Stephen Pendergrass said, "Today, I'm a disgruntled employee."
Before training security forces through special exercises, Pendergrass worked on explosives in the Army for 10 years.
"It was shortly after 9/11 I decided I wanted to serve my country," Pendergrass explained. "I still remember I was a junior in high school sitting in class, and the news ran down the hall and everybody turned on the TV. I don't think I'll ever forget the feeling."
Pendergrass, nearly 600 sailors and neighboring agencies are fighting to keep from feeling it again. The weeklong training happens annually at Navy bases nationwide, but they have not forgotten terrorists murdering by the masses.
On Wednesday, a U.S. official said ISIS is determined to strike this country.
Base security in Coronado is working to prevent something like that, and they are training to rapidly respond.
"Although we are firing blanks today when you have a weapon pointed at your … for a second you're thinking, is this real?" Pendergrass added.
That is the point of the realistic training; officials want to be ready if terror strikes.
Since sailors put themselves in harm's way, Pendergrass wants them as safe as they can be on home soil.
"The amount of sacrifice they put out … I think it's second to none," Pendergrass said.
Base workers are trying to avoid interruptions to daily work, but some delays are expected Thursday and Friday at Navy bases.
Naval Medical Center San Diego patients are urged to show up at least 45 minutes early for appointments.