(CNN) — President Barack Obama was briefed Sunday morning on the mass shooting in an Orlando nightclub, the White House said.
Obama is set to address the shooting at 12:30 p.m. CT in the White House briefing room, weighing in personally on the worst mass shooting in U.S. history.
“Our thoughts and prayers are with the families and loved ones of the victims,” White House press secretary Josh Earnest said in a statement. “The President asked to receive regular updates as the FBI, and other federal officials, work with the Orlando Police to gather more information, and directed that the federal government provide any assistance necessary to pursue the investigation and support the community.”
Lisa Monaco, Obama’s homeland security and counterterrorism adviser, briefed the President, Earnest said. He said Obama asked for regular updates as federal and state officials investigate the shooting, which killed 50 people and wounded at least 53 others.
Vice President Joe Biden has also been briefed on the shooting and canceled a planned trip to Miami, Florida, to attend a fundraiser for Democratic National Committee chairwoman, Rep. Debbie Wasserman-Schultz.
Biden “offered his prayers for all those killed and injured in the shooting and sends his condolences to all the families and loved ones of the victims,” according to a statement from his spokesman.
The political world began to react to the shooting at the LBGT nightclub in the early Sunday morning hours.
The LGBT congressional caucus issued a statement saying they were “horrified by the tragic shooting.”
“Though details are still emerging, an attack during Pride Month against Pulse, an iconic gathering place for LGBT Floridians, has a particularly insidious impact on our entire community. Our thoughts and prayers are with everyone affected by this tragedy,” said Roddy Flynn, executive director of the LGBT Equality Caucus.
Vermont Sen. Bernie Sanders called it “horrific” and “unthinkable” and said it underscores the need for gun control measures.
“Oh, it’s horrific, it’s unthinkable. And just hopes go out to all those who were shot that they can recover,” the Democratic presidential contender said Sunday on NBC’s “Meet the Press.”
“And I’ve got to tell you, 25 years ago, I believe that in this country, we should not be selling automatic weapons which are designed to kill people,” Sanders said. “We have got to do everything that we can on top of that to make sure that guns do not fall into the hands of people who should not have them, criminals, people who are mentally ill. So that struggles continues.”
Hillary Clinton, the presumptive Democratic presidential nominee, offered a tweet signed “-H” to indicate it was from her personally.
“Woke up to hear the devastating news from FL. As we wait for more information, my thoughts are with those affected by this horrific act,” Clinton wrote.
Donald Trump, the presumptive Republican presidential nominee, referred to the shooting as “possible terrorism.”
In a tweet Sunday morning, Trump said: “Really bad shooting in Orlando. Police investigating possible terrorism. Many people dead and wounded.”
He later added: “Horrific incident in FL. Praying for all the victims & their families. When will this stop? When will we get tough, smart & vigilant?”
He was one of the first politicians to react amid reports that federal and state law enforcement officials were investigating the mass shooting as an act of terrorism.
His reference to “possible terrorism” was a much more measured reaction than Trump issued a month ago after the EgyptAir flight crash, which he tweeted “looks like yet another terrorist attack” before authorities had addressed possible causes.
Florida Gov. Rick Scott pledged to devote “every resource available” to helping after the shooting.
“My prayers are with the victims’ families & all those affected by the shooting in Orlando. We will devote every resource available to assist,” Scott tweeted.
Republican National Committee Chairman Reince Priebus tweeted: “Our thoughts and prayers are with the victims of the tragic Orlando attack and their families.”
Florida Sen. Marco Rubio tweeted: “Our prayers are with those injured and killed early this morning in horrifying act of terror in Orlando.”
A top Senate Democrat, Chuck Schumer of New York, wrote on Twitter: “Horrified and saddened by the appalling attack at Orlando LGBT nightclub. Praying for the victims and their families.”
New York Gov. Andrew Cuomo said: “Saddened to hear of the senseless mass shooting in Orlando. My thoughts are with the victims, the injured and their loved ones,” he tweeted.