SAN FRANCISCO (CBS SF) — A crowd of several hundred people showed up in San Francisco’s Castro District Wednesday evening to protest President Donald Trump’s announcement that transgender individuals will no longer be permitted to serve in the U.S. military.

The emergency protest was organized by a group calling itself “The Resistance” via social media.

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The crowd numbering between 200 and 300 people had gathered in Harvey Milk Plaza, located at Castro and Market streets, at 6 p.m.

“Donald Trump announced this morning he will be reversing Obama’s policy and ban transgender folks from serving in the military,” organizers said on Facebook. “Please come to this emergency protest to show his administration and the world that San Francisco stands with the transgender community.”

The announcement came in a series of tweets from Trump around 6 a.m. Pacific time.

“After consultation with my generals and military experts, please be advised that the United States Government will not accept or allow … transgender individuals to serve in any capacity in the U.S. Military,” Trump wrote.

“Our military must be focused on decisive and overwhelming … victory and cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail,” he added.

The announcement has drawn ire from across the political spectrum, including state Sen. Scott Weiner, D-San Francisco, who called it a “bigoted move,” and even Republican U.S. Sen. John McCain, chairman of the Senate Armed Services Committee.

“The President’s tweet this morning regarding transgender Americans in the military is yet another example of why major policy announcements should not be made via Twitter,” McCain said in a statement.

“We should all be guided by the principle that any American who wants to serve our country and is able to meet the standards should have the opportunity to do so — and should be treated as the patriots they are,” he added.

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Trans veteran Theresa Sparks was drafted and already fought during one war in Vietnam. Now, thanks to President Trump’s ban, she says she is ready to fight a political battle.

“It was just outrageous. It’s like, I couldn’t believe it,” said Sparks. “I thought it was a joke at first. It just makes no sense.”

Since October, transgender military members have been able to receive medical care and officially change their gender identification in the personnel system. Now they won’t be allowed into the military at all. Experts say those who are already serving are wondering what their future holds- and if they’ll keep their jobs

“That means it’s time for a purge, said Aaron Belkin, Director of the Palmer Center. “There are thousands of transgender troops serving loyally and honorably and they’ve been serving openly all year and the president declared open season on them today. This is basically a witch hunt.”

The Palm Center studies minorities in the military.

Belkin told KPIX 5 Trump’s claims that transgender members disrupt service and their medical care is too expensive are both based on bogus information.

He said the White House claim that this is a move the military wanted is also false.

“This ban is Don’t Ask Don’t Tell 2.0 and is a shocking attack on loyally serving American troops, said Belkin.” This is not about the military. The military did a year of study and concluded inclusive policy works.”

Even local Republicans in San Francisco were speaking out against the ban.

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“It doesn’t matter if you wear a mustache or a dress,” said Jason Clark, Chairman of the San Francisco Republican Party. “If you’re willing to put your life on the line for this country and serve and you do your job well, that’s all that really matters.”