FARGO, N.D. (AP) – A 75-year-old Fargo man who started donating blood and platelets in his 20s has contributed more than 400 times. Gerry Hamm’s donations account for more than 50 gallons of blood. Hamm says he keeps returning to donate blood to help those in need. He encourages everyone who can to donate.

Blood transfusions are used to help patients experiencing trauma and other life-threatening situations. The American Red Cross said there’s a critical shortage of type O blood, and the organization has been urging eligible donors to help replenish the supply.

Katie Bartelson is a donor recruitment representative for blood service provider Vitalant. Bartelson says up to 90% of people will either know of someone or need to receive a blood transfusion themselves at some point in their life.