The tainted blood was discovered by the Tennessee Valley region of the Red Cross following reports of white particles in donated blood.
There have been no reports of harmful effects on patients.
On Friday the Red Cross warned all hospitals throughout Georgia and northern Florida not to use some of its donated blood, reported CBS News Correspondent Sharyl Attkisson.
The Food and Drug Administration and Centers for Disease Control and Prevention were testing the particles, which were not considered dangerous or infectious.
The quarantine has left the region dangerously low on red blood cells and plasma, the Red Cross said.
Some Southern hospitals canceled surgeries, and the Red Cross shipped blood from other regions to increase the supply.
Blood in bags manufactured by Baxter International Inc. had been found to be contaminated. A spokeswoman for Baxter said the particles were not related to the manufacturing of the bags. Baxter's test results could be ready Monday.
This is the latest in a series of safety problems for the agency. In January, Attkisson reported FDA inspectors found more than 200 safety violations by the Red Cross. Many of the violations were offenses the Red Cross has repeatedly been ordered to fix.
And last week, Atkisson reported other troubles have surfaced with the nation's blood supply and the way the Red Cross manages it.
Mark Cox helped run blood drives for the Boise, Idaho, Red Cross when he said he discovered a dangerous practice known as "overbleeds" -- too much blood taken from donors. It can make them sick and put those receiving the blood at risk for deadly clots.
Cox, a respected blood collector who's even cited in a published study, thought the overbleeds were accidental and notified his supervisors.
"My first complaint was verbal and I got no response for months, they just pretended like I didn't say anything," he told Attkisson.
Believing the public's health was at risk, Cox called a special National Red Cross hotline. The Red Cross started the hotline two years ago, hoping to help restore confidence in its handling of the nation's blood supply. The FDA has been suing the Red Cross for years for violating blood safety rules.
The Red Cross had promised the hotline would "add an extra layer of safety" and communications would be "strictly confidential".
But were they confidential? Not according to Cox.
"I thought once National found out everything would come to a screeching halt, the blood bags would be turned down, my bosses would be told they can't draw that much blood," Cox said.
The same day he made the call, his Boise bosses fired him for being "unprofessional."
But until the phone call, Cox had never had a bad job review. In fact, "I got an excellent job review and a big raise," he said.
CBS News reported earlier on another Red Cross blood worker, Joseph Szaller, who also alerted the Red Cross hotline to serious blood safety violations -- and got fired.
The National Red Cross says it's pure coincidence both men were fired right after they called the hotline. The charity now says Cox was let go to protect co-workers who were frightened by his alleged threats to "bring down the Red Cross".
Yet his unemployment claim states the Red Cross supplied "no evidence to support their reasoning for terminating" him.
Cox is now suing the Red Cross, saying he never dreamed he'd lose his job for following his conscience. And he questions a system where workers who are trying to protect the public, end up getting punished instead.