(The Hill) – In an extraordinary breach of decorum, Rep. Lauren Boebert (R-Colo.) yelled out at President Biden during his State of the Union address on Tuesday accusing him of putting American troops in coffins.

Biden was in the midst of discussing how many American troops stationed in Iraq and Afghanistan developed cancer from exposure to toxic smoke from massive burn pits.

“A cancer that would put them in a flag-draped coffin,” Biden said. “I know–“

“You put them in, 13 of them!” Boebert yelled out.

She appeared to be referencing the 13 American service members killed in a bomb attack in Kabul as the U.S. withdrew troops from Afghanistan in August. Biden did not mention the chaotic U.S. military exit from the country during his speech.

Attendees across the entire chamber turned in shock at Boebert for her outburst. A chorus of gasps and “whoa!” then erupted on the Democratic side of the chamber.

Biden continued to press on with his speech. Before Boebert’s interruption, Biden was explaining how the issue is close to home because his own late son, Beau Biden, may have been affected by toxic burn pits.

“One of those soldiers was my son, Major Beau Biden,” Biden said.

Beau Biden, an Army veteran who served in Iraq, died of brain cancer in 2015.

Boebert’s outburst wasn’t her only attempt to draw attention during Biden’s address to the joint session of Congress.

Boebert and Rep. Marjorie Taylor Greene (R-Ga.), another far-right House Republican who regularly stirs controversy, chanted “build the wall!” as Biden discussed his proposals for immigration reform.

Boebert was also wearing a black shawl with the words “drill baby drill” emblazoned on the back.

Other Republicans appeared to indirectly echo Boebert’s effort to draw attention to the 13 American service members who were killed in Afghanistan.

“To the 13 American families who lost loved ones in Afghanistan in August, you deserved to be recognized by the President tonight,” House Minority Leader Kevin McCarthy (R-Calif.) tweeted after Biden’s speech concluded. “Americans remember your sacrifice, and we are forever indebted to you.”

It’s not the first time that a lawmaker has breached decorum by yelling out during a presidential address.

In 2009, Rep. Joe Wilson (R-S.C.) interrupted a speech by then-President Obama during a joint session of Congress. Wilson shouted “you lie!” in response to Obama maintaining that proposed health care legislation would not provide free health coverage for undocumented immigrants.

Wilson apologized for his outburst shortly after Obama’s speech.

“This evening, I let my emotions get the best of me when listening to the president’s remarks regarding the coverage of illegal immigrants in the health care bill,” Wilson said in a statement at the time. “While I disagree with the president’s statement, my comments were inappropriate and regrettable. I extend sincere apologies to the president for this lack of civility.”

The House later passed a resolution of disapproval largely along party lines to formally reprimand Wilson for his behavior.