The Los Angeles area was hit by a magnitude 4.7 earthquake with its epicenter in Malibu, California, on Thursday morning, according to the US Geological Survey.

A 2.8 magnitude aftershock was recorded in Malibu two minutes after the first quake. A 3.4 magnitude quake was also recorded 12 minutes after the first.

The first Earthquake Early Warning System in the United States in California “provided advanced warning to millions of California residents,” Gov. Gavin Newsom’s office said in a statement.

The Governor’s Office of Emergency Services (Cal OES) estimates that millions of people have received wireless emergency notifications thanks to the public-private partnership between the state and Google, which integrated the alert software into Android phone operating systems.

Phones in the affected areas received alerts from the state’s MyShake app, which sent out 425,217 alerts. After the quake, there were more than 20,000 new downloads of the app in just three hours.

In addition to sending emergency notifications, California is also using the technology to automate protective measures such as opening fire stations, recalling elevators, turning off water and gas valves, closing gates on bridges and alerting staff at schools and medical facilities, Cal OES said in a statement.

“Even as the state battles wildfires, we must always be prepared for other potential disasters. Thanks to our Earthquake Early Warning System, millions of people in Southern California received alerts on their cell phones as the quake struck,” Newsom said in a statement.

The California Earthquake Early Warning System combines a smartphone application with traditional methods of delivering alerts and warnings, known as Wireless Emergency Alerts (WEA). The earthquake system uses ground motion sensors across the state to detect earthquakes before people can feel them, according to the governor’s office. Under state leadership, “50 percent more sensors have been installed since the program began, making the system more accurate and able to deliver warnings more quickly.”

According to the Los Angeles Fire Department, there was no significant damage.