Political figures have taken to Twitter to offer their thoughts over news of a reported "mass shooting" at a popular downtown area in Jacksonville, Fla., on Sunday.

At least four people were dead and 11 others were being treated, law enforcement sources told Fox News on Sunday.

White House press secretary Sarah Sanders said that President Trump has been briefed on the situation, and is monitorin itg.

"Horrifying news from #Jacksonville this afternoon," Sen. Marco Rubio, R-Fla., tweeted. "Have spoken to local authorities & am still awaiting more information on this shooting. Situation still unfolding, law enforcement is asking everyone to avoid the area. #Sayfie."

He later tweeted a follow-up message.

"Have confirmed @FBI & @ATFHQ are in contact & in coordination with local authorities to provide any & all federal resources needed to respond to #JacksonvilleLandingShooting," he shared.

Senior White House adviser Ivanka Trump tweeted her thoughts.

"As we await further details, our hearts are with Jacksonville and all those affected by today’s tragic mass shooting," she said.

Former Democratic National Committee chairwoman Donna Brazile also tweeted about the news.

"Prayers for the victims and those injured," she wrote. "Please heed the advice of law enforcement officials. #JacksonvilleLanding."

Rep. Ted Deutch, D-Fla., reacted on Twitter.

"Another mass shooting - this time in Jacksonville," he wrote.

Deutch addded, "First responders, doctors and nurses are acting heroically. We are deeply grateful to them."

He continued, "Politicians offering only thoughts and prayers are acting cowardly. We must demand more from them."

Deutch later posted another tweet.

JACKSONVILLE LANDING SHOOTING KILLS AT LEAST 4, SOURCES SAY; GUNFIRE HEARD AT GAMING TOURNAMENT

"My heart breaks for more of my fellow Floridians today," he said. "For more families whose lives will never be the same, for another grieving community, and for the generation raised in a country that has allowed horrific shootings to become commonplace, we must say, “enough.” ENOUGH!"

Florida Gov. Rick Scott tweeted about the situation as well.

"I’ve spoken to @JSOPIO Mike Williams to offer any state resources he may need," the Republican said. "[Florida Department of Law Enforcement] is currently responding, and I have spoken to FDLE Commissioner Rick Swearingen regarding the shooting in Jacksonville. We will continue to receive updates from law enforcement."

He has since tweeted that he has spoken with the city's mayor, Lenny Curry.

Rep. Charlie Crist, D-Fla., offered his prayers in a tweet.

"Devastated by reports of another mass shooting in Florida," he wrote. "Praying for all involved. But more than prayers, we need action to stop such senseless violence in our communities."

Rep. Darren Soto, D-Fla., also took to Twitter regarding the situation.

"Our prayers go out to those killed and injured in #Jacksonville shooting, and we hope shooter will be brought to justice. #Sayfie ⁦⁦@Everytown⁩ ⁦@CityofJax⁩," he said.

Florida Attorney General Pam Bondi shared her thoughts.

"Praying for Jacksonville and the victims of this horrific attack. My advocates are there assisting @JSOPIO—helping the victims," the Republican shared.

Sen. Bill Nelson, D-Fla., urged people to follow warnings from law enforcement.

"Word of another tragic mass shooting in our state brings shock and outrage," he tweeted. "Right now, law enforcement are doing their jobs under horrific circumstances and it’s important that people in the Jacksonville area heed their warnings."

Rep. Gregory Meeks, D-N.Y., opened up about his emotions over the incident.

"Once more left speechless and exasperated as yet another mass shooting claims young innocent lives," he said. "My heart is with all the victims and their families during this unimaginably painful time."

Rep. Keith Ellison, D-Minn., took to Twitter, as well.

"Another tragic loss of life to gun violence in Jacksonville today," Ellison, also deputy chairman of the Democratic National Committee, wrote. "We must keep fighting for common sense measures to keep dangerous weapons out of the hands of criminals and those who pose a risk to themselves or others."

Rep. John Rutherford, R-Fla., urged Twitter followers to adhere to guidance from the sheriff's office.

"Horrified by what has transpired at The Landing," he said. "As we pray for the victims and all the emergency personnel responding to this tragedy, please follow guidance from @JSOPIO as they work to secure the area."

Sen. Kirsten Gillibrand, D-N.Y., called for passing "common sense gun reform" in part of a tweet.

"We need to act now to save lives," she said.

Fox News' Katherine Lam, Travis Fedschun and Nicole Darrah contributed to this report.