"This is the type of incident that we prepare for on a regular basis, we train for, and we train with our friends over at the Los Angeles Police Department and other entities," said Matt Spence with the Los Angeles Fire Department.
Hospitals prepare as well. Dr. Angelique Campen is an assistant director of the emergency room at Providence St. Joseph Medical Center in Burbank, a disaster resource center where drills are conducted regularly. She says shootings pose extra challenges in mass casualty situations.
"Usually they require surgical intervention, so that's one thing that guides how many patients you can accept, is how many operating rooms you have available, how many surgeons you have available," she said.
Drills are conducted often and are based on certain scenarios, like a gunman opening fire at UCLA or a terrorist attack. These drills prepare first responders and law enforcement for the worst, and teach them to work together. Then there are organizations like the Red Cross, which sets up evacuation shelters and help victims in shock.
"After a disaster like that, it doesn't just affect the family or the friends of a victim, it affects the community, and that's where everyone needs to get together and just do things that comfort them," said Monica Diaz with the American Red Cross Los Angeles Region.
In the wake of the movie theater massacre that left a dozen people dead, first responders and emergency personnel can only hope they are left with more lessons about how to better save lives when the next tragedy happens.