A concerning shortfall in blood donations last month could stress the American Red Cross blood supply, the agency said.

The need for blood is constant, with someone needing a blood transfusion in the U.S. every two seconds, and the Red Cross collected at least 26,000 fewer blood donations than needed in May to meet the needs of patients.

Platelet donors are especially needed at this time. Donors can help ensure continuity for patients by making an appointment to give blood or platelets now and in the weeks ahead.

In thanks for taking time to help, everyone who gives blood, platelets or plasma in June will receive a $10 gift card by email to a merchant of their choice. People who come to give throughout June will also be automatically entered for a chance to win a backyard theater package. Details for both offers can be found at RedCrossBlood.org/June.