By using text messages, the city of Stockholm, Sweden is getting emergency responders to cardiac arrest victims faster.

Here’s how it works. Volunteers who are trained in CPR are added to a network called SMSlivräddare, (or SMSLifesaver). When a resident dials 112 (the equivalent of 911 in the states), a text message is sent to all CPR volunteers who are within 500 meters of the person needing emergency care. This way, a volunteer may get to the patient faster than an ambulance.

The likelihood of survival from cardiac arrest drops 10% for every minute it takes first responders to arrive. CPR administered by bystanders has been found to significantly increase the likelihood of survival, but not everyone feels comfortable doing it, or even knows how.

SMSlifesavers is run by Stockholm South General Hospital and the Karolinska Institute and currently has 9,600 registered volunteers. According to Quartz, there are about 200,000 Swedes who have undergone CPR training and could participate.

SMSlifesavers’ spokesperson, Dr. Mårten Rosenqvist, told Quartz that traditional ambulance services have trouble reaching cardiac arrest victims in teh Stockholm area due to lack of vehicles, traffic and other patient duties.