There does not appear to be enough donated blood to meet demand among hospitals and patients in need, according to the nonprofit.
More than 100 people donated blood in Hayward Sunday to help relieve a nationwide shortage.
The American Red Cross has issued an emergency call for blood donors after fewer people than expected donated in the last couple months.
The federal government is taking steps to keep the nation's blood supply from being tainted with the Zika Virus. Friday morning, the FDA advised all blood banks to start screening donations.
The ABC7 blood drive is underway in San Francisco, right across the street from our station until 3 p.m.
Blood donation centers in Northern California have issued an urgent plea for donors to come forward to address a severe nationwide blood shortage aggravated by the Zika virus.