Blood types O positive, O negative, B negative and A negative are especially needed, according to a news release from the Red Cross.

The agency is asking people who are eligible to donate to call the toll-free number and find a donation location close to them and give blood as soon as possible. Call 1-800 RED CROSS (800-733-2767) to schedule an appointment, or find more online: http://www.redcrossblood.org/.

Blood donations are down in the first five months of 2012 compared to the same period last year, say officials.