When a moderately strong earthquake shook Southern California on Monday, it was the elephants that immediately responded.

As a 5.2-magnitude earthquake struck near San Diego on Monday morning, a small herd of African elephants at the San Diego Zoo Safari Park reacted by forming a protective circle, video shows. They initially ran toward each other, spun around as if they were trying to figure out the source and then created a circle for protection.

The elephants probably had one of the biggest responses to the earthquake at the park, said Mindy Albright, curator of mammals at San Diego Zoo Safari Park located 40 minutes north of the zoo. Other animals just froze for a moment.

“It’s so cool because elephants are so much like humans in how they come together as a family unit,” Albright said. “They have such a tight family unit [and] that survival strategy is really strong with them.”

Elephants can feel sound through their feet, Albright explained. When something alarming happens, like a predator or unknown environmental cue such as an earthquake, they surround the young to protect them from the danger — called an “alert circle.”

This group of elephants has circled up in response to an earthquake before.

Sometimes, the elephants make an alarm call in a register beyond human detection to push the herd into a circle, which Albright said may have also happened here.

The youngest elephant, named Mkhaya, stood in the center of the circle between the two moms. But, in an unusual move, another youngster, named Khosi, stayed on the outside like an adult. Another elephant called Zuli kept touching his face, as if to check on him and ask why he wasn’t in the middle with the other young ones, said Albright.

“It’s really neat to see how they react and, as they grow up, [how] their social responsibility is within the herd might change,” said Albright. For example, she asked if they remain in the center of that alert circle or move to the perimeter protecting the younger calves.

The video of the elephants show that once they formed a circle, the animals became still for a moment and appeared to be listening. They were trying to feel additional environmental cues with their feet to gauge what to do next, Albright said. They went back to normal after about four minutes, but remained closer to one another.

As the earthquake occurred, wildlife-care specialists were cleaning the other elephant habitat. After the tremble, they checked the herd and made sure nothing was damaged by the quake.

The park has a total of eight elephants. Three were rescued in 2003 from Eswatini in southern Africa, and the rest were born at the park. Albright said the park’s goal is to protect the animals and learn more about their behaviors — including to how they will respond to unknown dangers, like Monday’s quake.

“For them to just be so in tune with their environment and paying attention to the environmental cues, it’s really something that you want to see them still home in on,” said Albright. “It’s a measure of their health to see them respond like this.”