Emergency responders and schools across the state took part in what is considered the largest earthquake drill in the world.
When the clock struck 10:20 Thursday morning, students, teachers, and administrators at Yokomi Elementary School in Fresno joined millions of Californians, in all 58 counties, in a drill on earthquake safety.
The message "drop, cover and hold on." Detailed instructions on what to do the moment the earth starts to shake.
Bruce Thele, Yokomi Elementary Principal said, "As schools we have to be prepared for all sorts of disasters. We do fire drills every month, lockdown drills, but in California especially, we need to be prepared in case of an earthquake."
More than 430-thousand people from the Central Valley participated in the Great California Shakeout.
The majority of them, students in schools, colleges and universities. Businesses and government agencies also took part.
Thele said, "We have to make sure we're very precise and orderly, especially if we have to evacuate."
Principal Bruce Thele says this was the first year his school participated in the drill.
Because fires often follow earthquakes, Thele had his students also practice the school's safety plan for evacuating a burning building.
Students we talked with thought it was exciting to be involved in the largest earthquake drill in US history.
Jacqueline Cardenas, sixth grader said, "It's pretty cool cuz all over the state is doing it at the same time as us."
Many of them said they felt better prepared to survive and recover after California's next big quake.
Kevin Zamora, sixth grader said, "I think it's good for the environment to be ready cuz it could happen at anytime."