U.S. Secret Service Director Kimberly Cheatle said her agency welcomes the independent review announced by President Joe Biden.

“We understand the importance of the independent review announced by President Biden yesterday and will participate fully,” Cheatle said in a statement issued on Monday. “We will also work with the appropriate Congressional committees on any oversight action.”

Questions have been raised about how the suspect in the assassination attempt was able to climb on top of a roof near former President Donald Trump’s rally on Saturday.

“The Secret Service is working with all involved Federal, state and local agencies to understand what happened, how it happened, and how we can prevent an incident like this from ever taking place again,” Cheatle said.

-ABC News’ Pierre Thomas and Kevin Shalvey

Shares of Trump Media & Technology Group, a company majority owned by former President Donald Trump, rose about 50% in early trading.

The stock, which is traded under the DJT ticker, climbed to about $45 a share in pre-market trading on Monday, the first day the market will be open after the attempted assassination.

-ABC News’ Kevin Shalvey

King Charles wrote a private letter to former President Donald Trump on Sunday, Buckingham Palace said in a statement.

The correspondence was delivered via the U.K. Embassy in Washington, D.C., the palace said on Monday.

"We do not divulge contents of such private correspondence, but safe to surmise that the sentiments are in keeping with those communicated by the PM," the palace said, a reference to Prime Minister Keir Starmer.

The prime minister said Sunday he was "appalled" by the assassination attempt.

-ABC News' Zoe Magee

Former President Donald Trump praised Secret Service agents who acted quickly to protect him and get him offstage following the attempt on his life at his Saturday rally in Pennsylvania.

"They did a fantastic job," he said in an interview with the New York Post on Sunday.

Reflecting on the shooting, Trump said, "I'm not supposed to be here, I'm supposed to be dead."

Trump praised the crowd at his rally for how they reacted in the moment.

"A lot of places, especially soccer games, you hear a single shot, everybody runs. Here there were many shots and they stayed," he said, adding, "I love them. They are such great people."

In the interview, which the Post reported also included a reporter from the Washington Examiner, Trump addressed the call he received from President Joe Biden saying it was "very nice."

Sen. Lindsey Graham, who the Post reported was on the flight with Trump, said of the former president, "He feels like he has a new lease on life."