The Seal Beach Naval Weapons Station took part in the largest security exercise of the year as Navy and local agencies worked together, training for potential threats.
Officials conducted active shooter drills to prepare for a shooter in any scenario.
The drill was taken seriously, especially following the mass shooting at the Washington Navy Yard last year. Thirteen people, including the shooter, were killed in that incident.
"You always have to be prepared, thing happen that are not predictable," said Capt. Tripp Hardy, the commanding officer of the Seal Beach Naval Weapons Station.
In this type of scenario, a homegrown extremist group has taken hostages inside a warehouse. Nearby, a man is found dead. He's surrounded by white powder and dead birds.
"He has symptomology that's consistent with some type of chemical agent," said Orange County Sheriff's Department Lt. Joe Balicki.
The base is put on lockdown as first responders arrive. The area of the potential weapon of mass destruction is contained.
The participants know it's a drill, but have not been told exactly what to expect.
This is the first time that local law enforcement like Seal Beach police and the Orange County Sheriff Department's SWAT team have taken part in a drill on the naval base.
Officials say it's a chance to improve cooperation between different agencies to be better prepared for a real crisis.
"It's also resources that no one agency can afford to have to cover an entire contingency, you really have to have mutual support," said Hardy.
A few Orange County sheriff's SWAT operators are in place, but they can't wait for others - once shots are heard.
SWAT moves in with the help of Seal Beach base security officers. The armed suspect is shot and killed.
Three hostages are unharmed. At the other location, first responders take samples to figure out what they're dealing with - exercising skills that could save lives.
"It allows us to maybe prevent it for the next time or at least have a quicker more thorough response to it," said Balicki.