Thousands of Florida residents formed long lines around blood centers in Orlando, Florida after an urgent call for donations in the wake of the worst mass shooting in US history.

"The line to donate blood in #orlando today
via George Takei pic.twitter.com/u1W6dPbjlR

— Renee PurrpleCatmama (@PurrpleCatMama) June 12, 2016

Yet many are expressing anger over the federal government's continuing ban on blood donations from gay and bisexual men. 

Orlando Hospitals need blood donations to help save gay people.

Yet gay people can't give blood to help their own. Because they're gay.

— Bobby Blanchard (@bobbycblanchard) June 12, 2016

The ban began in 1983, yet President Obama’s administration has made only very slow changes to the rule, including allowing gay and bisexual men to donate blood if they have been celibate for one year.

The ban is keeping gay men from helping their friends and family who may have been victims of today's attack, which occurred during LGBT Pride Month.

Huge awful irony: gay men can't give blood after Orlando's gay night club shooting because of the "Gay Blood Ban." https://t.co/AERLN5w30s

— Marc Caputo (@MarcACaputo) June 12, 2016

The ban on gay men donating blood is nothing short of fear-driven homophobia disguised as public health policy https://t.co/Nm2MmvEE1G

— Miles Kenyon (@MilesJKenyon) June 12, 2016

Rumors on social media suggested that the FDA rules against gay/bi men making blood donations had been lifted today. In a 12:48 PM Tweet, Orlando's OneBlood denied those rumors were true:

All FDA guidelines remain in effect for blood donation. There are false reports circulating that FDA rules were being lifted. Not true.

— OneBlood (@my1blood) June 12, 2016

In June 2013, the American Medical Association (AMA) issued a statement calling on the FDA to change the policy, stating that "The lifetime ban on blood donation for men who have sex with men is discriminatory and not based on sound science."