The San Diego Blood Bank put out a call Thursday for donors with Type O blood, especially O-negative, citing a "critical need" at area hospitals.
The supply of O-negative blood shrunk because of the Labor Day holiday weekend and an influx of trauma patients, according to the Blood Bank.
When a trauma patient arrives at a hospital, there usually isn't time to check their blood type, so transfusions are performed with O-negative. That means O-neg, the universal donor type of blood, is always in high demand.
The public can give blood at one of the organization's donation centers or community drives. Times and locations are available online at www.SanDiegoBloodBank.org or calling (800) 469-7322.