At McClellan Park, a bus driver makes the call.
"I've been in a major accident."
An orange school bus is on its side. Students, played by actors, call out in pain or lie motionless. Smoke, played by liquid nitrogen- pours from the engine.
More than 100 employees of the Sacramento City Unified School District and local police and fire agencies then watch and wait for someone to respond to the cries for help.
Six minutes seem like hours. In the following 90 minutes, students are treated at the scene by Sacramento City Fire, pronounced dead, or taken to local hospitals with injuries by a Cal Star helicopter.
The driver of the van that hit the bus is arrested by the CHP for driving under the influence.
When it's over, Doug Morse with the Sacramento Police Department says the simulation went well.
"I guarantee you that everyone of these agencies that are out here has a plan. It does us no good to have those plans in place if we don't get together and practice and not practice on our own, but practice in a coordinated effort. Because I'll also guarantee you when a tragic incident like this occurs, we're all gonna need to come together and bring our plans to the table and put 'em into action."
Most of the police and firefighters are used to this type of scenario. But Tarig Elsiddig of the Celebration Arts Institute says the actors who played the students were not.
"It got very real at times and people actually did break down. Some people didn't even participate when they came here originally. They actually opted out before we began the process. So, yeah, it was really tough for some people. It can get absolutely real for some people."
Gabe Ross is with the school district. He says the exercise is valuable for the practice it provides first responders, and the information it gives school staff.
"School bus drivers, dispatch employees, bus attendants: they're not really prepared for the chaos that is a real emergency situation. So, to witness it first hand, to see what it looks like in 'real life', really valuable for them. They'll be able to process how they'd handle this situation.
The California Highway Patrol, Sacramento City Fire Department and Sacramento Police Department took part in the drill.
The agencies will debrief and identify ways to improve what they do and how they interact with other departments.