Donald Trump on Sunday sought to rally his supporters with news of a possible second attempt on his life, blasting out a campaign fundraising appeal that said “there are people in this world who will do whatever it takes to stop us” as his advisers urged campaign staff to be “vigilant” about security.

Trump was golfing at his West Palm Beach, Fla., club on Sunday when a Secret Service agent spotted a man with a rifle with a scope in the tree line, officials said. Secret Service opened fire, and the suspect was eventually apprehended. The FBI is investigating the incident as a possible assassination attempt, but authorities have released little information about the suspect.

Trump was uninjured, according to his campaign. But the episode renewed questions about Trump’s safety.

The Secret Service is probing breakdowns in security that allowed a gunman to fire down from a nearby rooftop at a July 13 Trump rally in Butler, Pa., killing an audience member and leaving Trump bloodied. Investigators have not pinpointed what drove the now-deceased shooter, Thomas Matthew Crooks, who had pictures of both Biden and Trump on his phone and did not show signs of a political motive.

“[We] must ask ourselves how an assassin was allowed to get this close to President Trump again?” Rep. Elise Stefanik (R-N.Y.) said in a statement. “There continues to be a lack of answers for the horrific assassination attempt in Pennsylvania and we expect there to be a clear explanation of what happened in Florida.”

Palm Beach County Sheriff Ric Bradshaw said that if Trump was still president, “we would have had the entire golf course surrounded. Because he’s not, security is limited to the areas that the Secret Service deems possible.”

Trump’s top campaign advisers, Susie Wiles and Chris LaCivita, called the suspect an “evil monster” in an email to campaign staff and said no one on the golf course or accompanying Trump was hurt.

“This is not a matter that we take lightly,” they wrote in an email, according to a person familiar with it who spoke on the condition of anonymity to discuss internal communications. “Your safety is always our top priority. We ask that you remain vigilant in your daily comings and goings. Be observant and maintain a constant level of situational awareness.”

Democratic leaders denounced violence after the shooting at Trump’s rally and did so again on Sunday. It is not yet clear if the suspect in the golf club incident had a political motive. But Trump’s campaign has repeatedly accused Democrats of endangering Trump’s life by calling him a threat to democracy — a reference to Trump’s failed efforts to overturn the 2020 election — and LaCivita echoed that message on Sunday.

He shared a video in which Sen. Bernie Sanders (I-Vt.) calls Trump “a threat to our democracy” and says, “we together must do everything in our power to defeat Trump and his MAGA allies this November.” In another post, LaCivita predicted Trump’s critics would not tone down their rhetoric.

The July 13 shooting helped rally Republicans behind Trump and seize political momentum just before he formally accepted the GOP nomination.

Trump’s campaign moved quickly on Sunday to solicit a new wave of donations, sending out an email to supporters that read: “Nothing will slow me down. I will NEVER SURRENDER! I will always love you for supporting me. Unity. Peace.”

The message linked to a fundraising page that added, “there are people in this world who will do whatever it takes to stop us. I will not stop fighting for you.”

Texts from the campaign shared the fundraising link with the same call for “UNITY. PEACE.”

Trump also called for unity after the rally shooting in Pennsylvania and praised law enforcement repeatedly for protecting him. But in the weeks that followed he stoked unfounded claims about the attack as well.

He suggested without evidence that his political rivals, President Joe Biden and Vice President Kamala Harris, personally made it more difficult for the Secret Service to protect him leading up to the Butler shooting. And he did not push back when a right-wing podcast host, Monica Crowley, accused government agencies of “slow-walking” evidence and asked Trump, “Does it look increasingly to you like this was a suspicious, maybe even inside job?”

“It’s very suspicious,” Trump said. “The more you see it, the more you start to say, ‘There could be something else.’”

Trump and his campaign said little about the Sunday golf course incident in the hours immediately afterward. Early in the evening, Trump had yet to write anything about it on Truth Social, his social media site where he posts prolifically.

On the social media site X, Trump’s “War Room” account shared a brief, initial campaign statement about shots fired and reposted a message from Trump’s running mate, Sen. JD Vance (R-Ohio).

“I’m glad President Trump is safe. I spoke to him before the news was public and he was, amazingly, in good spirits,” Vance wrote early Sunday evening. “Still much we don’t know, but I’ll be hugging my kids extra tight tonight and saying a prayer of gratitude.”

Sen. Lindsey Graham (R-S.C.), a close Trump ally, also said he spoke with Trump. “He’s in good spirits and he is more resolved than ever to save our country,” Graham wrote on X.

Trending topics on the social media site reflected the country’s polarized response. “Pray for President Trump” trended as well as “Staged” — as some social media users promoted the baseless claim the golf course incident was staged.

Harris, the Democratic nominee for president, said on social media that she was briefed on the matter and glad Trump is safe. “Violence has no place in America,” she wrote.

Harris’s running mate, Tim Walz, the Democratic governor of Minnesota, shared a similar statement: “Violence has no place in our country. It’s not who we are as a nation.”

House Speaker Mike Johnson (R-La.) said he and his wife spent “a few hours” with Trump at Mar-a-Lago after the shooting. Johnson wrote on social media that he and his wife “are thanking God for protecting [Trump] today — once again,” and said, “No leader in American history has endured more attacks and remained so strong and resilient. He is unstoppable.”

Trump’s advisers were relatively quiet on social media immediately after the incident. But Dan Scavino Jr., a senior adviser on the campaign, alluded to Trump’s words right after the Pennsylvania rally shooting, which became a political rallying cry. “FIGHT, FIGHT, FIGHT!!!!!” he wrote.

Isaac Arnsdorf contributed to this report.