LGBT Groups, Celebs and Public Figures Pay Tribute After 49 Victims Killed in Orlando Nightclub Shooting

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America woke up to the devastating news that the worst mass shooting in U.S. history occurred early Sunday morning, when 50 people were killed, including the shooter, and 53 injured inside Pulse, a gay nightclub in Orlando, Florida.

Both the Florida governor and city of Orlando have declared states of emergency, as authorities are considering the deadly incident a domestic terrorist attack.

"We are dealing with something we never imagined. Because of the scale I have called Governor Scott to request a state of emergency and we are issuing a state of emergency in the City," Orlando Mayor Buddy Dyer stated over a series of seven tweets, with the last included the hashtag "#PrayforOrlando." "This allows us to bring additions resources to support our efforts. Our focus in the coming hours will be identifying the victims and notifying the families... The identification process may take some time. We ask for your patience as we want to be accurate. I continue to be proud of how our community has responded."

NEWS: 50 Dead in Orlando Gay Bar Shooting

On Sunday, Orlando Police Chief John Mena told reporters that the shooter -- who has been identified as 29-year-old Omar Mateen of Port St. Lucie, Florida -- had a handgun and assault rifle on him, as well as an additional weapon. "It appears he was organized and well-prepared," the chief said.

According to CBS News, Mateen called 911 at the time of his attack in order to pledge his allegiance to ISIS, and he also mentioned the Boston bombers.

The mass shooting came on the heels of Washington, D.C. and Los Angeles celebrating their own LGBT pride festivals, with the city of West Hollywood still going forward with plans for their annual parade on Sunday.

Many celebrities, public figures, and LGBTQ groups quickly took to social media following news of the mass shooting, and a Go Fund Me page has been set up by Equality Florida, the state's LGBT civil rights organization, to support victims of the shooting.

The Human Rights Campaign reacted to media reportson Sunday morning, noting that Pulse "serves the area's LGBTQ community." "We are devastated by this tragic act of violence," HRC President Chad Griffin said in a statement. "We are grieving for the victims and our hearts are broken for their friends, families, and for the entire community. This tragedy has occurred as our community celebrates pride, and now more than ever we must come together as a nation to affirm that love conquers hate."

GLAAD also quickly took to Twitter to "stand in solidarity with the LGBTQ community in #Orlando."

Backstreet Boys member and Orlando native Howie Dorough tweeted, "So sad to hear about the shootings this weekend in my hometown. My heart goes out w prayers to the victims, families, friends & community."

Matt Bomer shared a similar sentiment, writing, "My heart goes out to all those affected by this terrible tragedy in Orlando. There are no words. Sending love and prayers."

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Ellen DeGeneres simply tweeted, "Sobbing," while Bravo's Andy Cohen asked, "If we can't get rid of guns, can we please end homophobia?"

See even more reactions below.

Orlando is still reeling from the Friday night shooting of 22-year-old singer Christina Grimmie, who was killed during a meet-and-greet after her concert at Plaza Live. Find out what we know so far in the video below.