(CNN) One Friday night this month, Madeline Dahl, a 23-year-old nurse in the cardiology ICU at Seattle's University of Washington Medical Center, received an alert on her cell phone: Someone nearby needed help. Having just finished her shift, Dahl dropped what she was doing at the hospital and ran down five flights of stairs to the street. "It was right during a huge storm, so it was raining, and I was trying to figure out where they would be," she said. "And then I saw Zach was bent over somebody on the ground, so I ran over." Zach Forcade, a 27-year-old medical student, hovered above a man beside a bus stop outside the hospital. Forcade had seen Stephen DeMont fall to the ground and shouted to a passer-by to dial 911 before he performed chest compressions, trying to keep DeMont's heart beating.PulsePoint alerts CPR-trained people that aid is needed nearbyThe app means people in cardiac arrest can get help quicker
DeMont feels grateful to _ and Dahl for the immediate CPR he received. Though she herself didn't perform _, she helped Forcade by making sure DeMont's air passage remained clear and by counting compressions. Though she herself didn't perform CPR, she helped Forcade by making sure _'s air passage remained clear and by counting compressions. DeMont feels grateful to Forcade and Dahl for the immediate _ he received. Approximately 900,000 people have downloaded the app, which is open to anyone who's certified in _ and wants to help. The doctor took over _ duty until emergency services arrived.