A mass shooting at a popular gay club in Orlando, Florida, left 50 people dead early Sunday morning, including the gunman, according to officials. An investigation is ongoing into the reason for the rampage, and authorities are looking into the possibility that it is terrorism-related.

Politicians were quick to offer their somber support for people in Orlando.

Presumptive Democratic nominee Hillary Clinton personally took to Twitter to weigh in on the "devastating news" from Florida early Sunday morning.

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. -H — Hillary Clinton (@HillaryClinton) June 12, 2016

After more information of the shooting came out, Clinton issued another statement some hours later, declaring the murders "an act of terror" and "also an act of hate."

"For now, we can say for certain that we need to redouble our efforts to defend our country from threats at home and abroad. That means defeating international terror groups, working with allies and partners to go after them wherever they are, countering their attempts to recruit people here and everywhere, and hardening our defenses at home," she said. The former secretary of state specifically commented on the attack of an LGBT nightclub during Pride Month.

"To the LGBT community: please know that you have millions of allies across our country. I am one of them. We will keep fighting for your right to live freely, openly and without fear. Hate has absolutely no place in America," she said.

She concluded her statement with a call for stricter gun control reforms, saying the incident "reminds us once more that weapons of war have no place on our streets."

According to a campaign press release, Clinton's June 15 campaign event in Green Bay, Wisconsin will be postponed. President Obama was scheduled to attend.

Donald Trump, the Republican party's presumptive nominee, also commented on the "really bad shooting" via the social media platform.

Really bad shooting in Orlando. Police investigating possible terrorism. Many people dead and wounded. — Donald J. Trump (@realDonaldTrump) June 12, 2016

A few hours later, Trump sent another message on Twitter asking, "When will we get tough, smart & vigilant?'

Horrific incident in FL. Praying for all the victims & their families. When will this stop? When will we get tough, smart & vigilant? — Donald J. Trump (@realDonaldTrump) June 12, 2016

And in another message, Trump touted the "congrats" he had received for "being right on radical Islamic terrorism."

Appreciate the congrats for being right on radical Islamic terrorism, I don't want congrats, I want toughness & vigilance. We must be smart! — Donald J. Trump (@realDonaldTrump) June 12, 2016

Just minutes before President Obama was scheduled to address reporters from the White House regarding the Orlando shooting, Trump once again fired off another critical tweet:

Is President Obama going to finally mention the words radical Islamic terrorism? If he doesn't he should immediately resign in disgrace! — Donald J. Trump (@realDonaldTrump) June 12, 2016

Trump also tweeted out unconfirmed reports of the shooter declaring "Allah hu Akbar" as he opened fire on the nightclub.

Reporting that Orlando killer shouted "Allah hu Akbar!" as he slaughtered clubgoers. 2nd man arrested in LA with rifles near Gay parade. — Donald J. Trump (@realDonaldTrump) June 12, 2016

In a longer statement sent out by his campaign Sunday afternoon, Trump repeated his call for the president to step down, slamming the chief executive for having "disgracefully refused to even say the words 'Radical Islam.'" He called on Clinton to get out of the general election race for the same reason.

"Because our leaders are weak, I said this was going to happen - and it is only going to get worse," he said. "I am trying to save lives and prevent the next terrorist attack. We can't afford to be politically correct anymore."

Trump further implied that he would decrease immigration from the Middle East because "since 9/11, hundreds of migrants and their children have been implicated in terrorism in the United States."

"Hillary Clinton wants to dramatically increase admissions from the Middle East, bringing in many hundreds of thousands during a first term," he charged. "And we will have no way to screen them, pay for them, or prevent the second generation from radicalizing."

Trump further tweeted that he "called" the attack and "asked for the ban" of any Muslims entering the U.S.

What has happened in Orlando is just the beginning. Our leadership is weak and ineffective. I called it and asked for the ban. Must be tough — Donald J. Trump (@realDonaldTrump) June 12, 2016

The suspected shooter, Omar S. Mateen, was an American citizen born in New York to Afghan parents, according to the FBI.

Responding to Trump, Clinton's communication director slammed the billionaire in her own statement Sunday evening.

"Donald Trump put out political attacks, weak platitudes and self-congratulations," Jennifer Palmieri wrote of his response to the Orlando shooting. "Trump has offered no real plans to keep our nation safe and no outreach to the Americans targeted, just insults and attacks. In times of crisis more than ever, Americans are looking for leadership and deserve better."

Speaking to NBC's "Meet the Press" early Sunday, Democratic presidential candidate Bernie Sanders called the murders "horrific" and "unthinkable."

"Our -- just -- hopes go out to all those who were shot that they can recover," Sanders said, before discussing his previous support for bans on selling automatic firearms in the U.S.

"Twenty-five years ago, I believed that in this country that we should not be selling automatic weapons which are designed to kill people," the Vermont senator added. "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 those who should not have them: criminals, people who are mentally ill. So that struggle continues."

Gary Johnson, the Libertarian party's presidential nominee and a former governor of New Mexico, called the slaughter "both cowardly and infuriating" but warned against politicizing the situation.

"In this immediate aftermath of what is clearly a tragic and despicable attack, our thoughts must be with the victims. Regardless of what the motivation is ultimately found to be, this violence against innocent people simply going about their lives is both cowardly and infuriating," Johnson said in a statement released Sunday afternoon. "We must allow the authorities to do their jobs, understand how this attack came about, and then respond accordingly. It is not a time to either politicize or jump to conclusions."

The Orlando shooter put up a protracted gun battle with police, according to a U.S. intelligence source. He was heavily armed with an assault rifle, a handgun, and a "device" of some kind that officials believed was a threat.

President Obama was briefed Sunday morning by Lisa Monaco, assistant to the president for homeland security and counterterrorism top homeland security officials, according to a statement from the White House press secretary. The president requested to receive regular updates on the situation as the FBI, the Orlando police, and other federal officials continue to carry out their investigation.

Governor Rick Scott speaks on the Orlando nightclub mass shooting

Appearing from the White House Sunday afternoon, the president addressed reporters on the shooting.

"This was an act of terror and an act of hate," Mr. Obama said. "The FBI is appropriately investigating this as an act of terrorism." He acknowledged that it was an "especially heartbreaking day" for the LGBT community.

Of the suspected shooter, the president said that "what is clear is that he was a person filled with hatred." Mr. Obama named the Orlando massacre as "the most deadly shooting in American history" and noted that the killer was armed with at least two guns. He said the day further served as a reminder "of how easy it is for someone to get their hands on" a weapon.

He also seemed to chastise legislators for their inability to agree on passing stricter gun reforms.

"We have to decide if that's the kind of country we want to be -- and to actively do nothing is a decision as well," Mr. Obama said.

The president issued a proclamation Sunday for the American flag to be flow at half-staff at the White House and on all public buildings and grounds (including military posts, naval stations, U.S. embassies and facilities abroad) until sunset of June 16.

Vice President Joe Biden was also briefed Sunday by his national security advisor.

In a statement from the vice president's spokesperson, 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."

In a statement from the vice president himself, Biden offered his own prayers and condolences for the Orlando shooting victims but noted that "our prayers are not enough to end these kinds of senseless mass shootings."

"The violence is not normal," he said, "and the targeting of our lesbian, gay, bisexual, and transgender Americans is evil and abhorrent."

He is closely monitoring the situation and will continue to receive regular updates as well. The vice president, who was scheduled to attend a fundraiser for Democratic National Committee chairwoman Debbie Wasserman-Schultz in Miami Sunday, will instead head to Washington, D.C.

Other local politicians offered up their own prayers for the families of the shooting victims, including Florida Gov. Rick Scott, who pledged to "devote every resource available" to assist.

My prayers are with the victims' families & all those affected by the shooting in Orlando. We will devote every resource available to assist — Rick Scott (@FLGovScott) June 12, 2016

The Republican governor declared a state of emergency later in the day.

In an extended statement, Scott commented on the "act of terror."

"This is a time of great tragedy, and in every tragedy, there is a flood of sadness, confusion and despair," he said. "But, this is an attack on our people. An attack on Orlando. An attack on Florida. An attack on America. An attack on all of us."

He also issued a warning against those who may try to commit other mass acts of violence: "To the people who did this or may be thinking about doing something similar: you don't want to commit an act of terror in our state. In Florida, our justice system is swift and our penalties are severe. We are at a 45-year crime low and proud to be a safe state for our 20 million residents and 100 million tourists."

Florida Sen. Marco Rubio, once a candidate for president, tweeted out his own call for central Florida residents to donate blood after several dozens were rushed to local hospitals.

If you live in Central Florida, blood donations are needed after mass shooting at #PulseNightclub https://t.co/g0Hg5FK1sY — Marco Rubio (@marcorubio) June 12, 2016

Our prayers are with those injured and killed early this morning in horrifying act of terror in Orlando. — Marco Rubio (@marcorubio) June 12, 2016

Rubio, who sits on the Senate Select Committee on Intelligence, released a fuller statement later in the day discussing the threat of domestic terrorism.

"Confronting the threat of violent homegrown ‎radicalization is one of the greatest counterterrorism challenges our law enforcement and intelligence community faces," he said. "‎We must do more at every level of government and within our own communities to identify and mitigate this cancer on our free society and prevent further loss of innocent life."

Our community experienced a horrific crime today. Our hearts & prayers are with the victims and their families. — Mayor Buddy Dyer (@orlandomayor) June 12, 2016

Despite the fact that tonight's crime will have a lasting effect, we are a strong community. — Mayor Buddy Dyer (@orlandomayor) June 12, 2016