A new app that recruits Good Samaritans into volunteers for medical emergencies has already saved thousands of lives.

When an ambulance is dispatched to someone suffering a life-threatening emergency like a cardiac arrest, the “GoodSAM” app sends out a cellphone alert to first responders and medically trained civilians who are in the vicinity of the person needing help. The Ambulance Victoria states that for every minute a person in cardiac arrest does not get CPR, their chances of survival decrease by 10 percent. That’s why this app is crucial, as it is allowing regular Good Samaritans to save lives in an instant.

The app recently made headlines when a 49-year-old man collapsed at his Melbourne home in the middle of the night. A paramedic who lived nearby received an alert about him on her phone, and she immediately rushed to help him.

“I didn’t even take the time to get out of my pajamas,” the paramedic said. “I just threw on a hoodie and went down to [his] house.”

This paramedic ended up saving the man’s life, and she never would have even known he was in trouble were it not for the app. Victorian Health Minister Jenny Mikakos said that this is just one of the many success stories from this app, which has saved 20 people in this area alone since the start of the year.

Though the app originally limited it’s participants to nurses and professionally trained medical professionals, anyone with basic CPR and first aid training skills can now volunteer as well. As of this writing, over 40,000 trained volunteers are registered with the app’s international alert system, and they have already responded to roughly 8,000 alerts.

Find out more about this in the video below.