If you arrive at the scene of an accident where several people are in need of first aid, you should not help the first person you see who looks to be injured. Rather, you should prioritize the person in most urgent need of help. To prioritize correctly, you should follow LABC.
LABC is an abbreviation that stands for: Life-threatening situation, Airways and breathing, Bleeding, Circulatory shock. It also tells you in which order to prioritize in the event of an accident. Life-threatening situations have the highest priority, Airways and breathing problems have the second highest priority and so on. In this case, you should first help the person who has stopped breathing.