PHOENIX -- The largest blood drive in Arizona was held Sunday while the state's blood banks battle a massive shortage.
The holiday season always brings a drop in donations, but United Blood Services Arizona said demand outweighed donations by a 2-to-1 ratio since Dec. 25.
To meet current demand, UBS said about 1,500 Arizonans will have to donate blood. All blood types are needed, but O-negative, the universal blood type, is the one used most.
The UBS' "Saving Arizona" drive was held Sunday morning at the Tempe Center for the Arts.
Spokeswoman Sue Thew said the event had 373 people sign in to donate blood, and that the result should be at least 250 successful donations.
"We won't know exactly how much blood until results come back from the lab in the morning," Thew said Sunday.
UBS said that if people weren't able to make it Sunday's event, they can still give blood at one of six Valley UBS donor centers later in the week.
All donors through Jan. 15 will receive a voucher for a one-day gate pass to the upcoming Waste Management Phoenix Open.
Donors can make appointments by calling 1-877-UBS-HERO or visiting BloodHero.com to register and find the nearest location.