Rep. Ilhan Omar on Wednesday accused President Trump of spreading “lies that put my life at risk” after the president retweeted a post falsely claiming that the Minnesota Democrat “partied on the anniversary of 9/11.”

Omar said the video of her dancing was taken not on the anniversary of the Sept. 11, 2001, attacks but at a Congressional Black Caucus event. Earlier Wednesday, Trump had retweeted a post by conservative actor and comedian Terrence K. Williams claiming that the video of Omar dancing was taken on the anniversary of the attacks. The original video appears to have been taken Sept. 13.

“This is from a CBC event we hosted this weekend to celebrate black women in Congress,” Omar said in a tweet. “The President of the United States is continuing to spread lies that put my life at risk. What is Twitter doing to combat this misinformation?”

In his message retweeting Williams on Wednesday morning, Trump had claimed: “Ilhan Omar, a member of AOC Plus 3, will win us the Great State of Minnesota. The new face of the Democrat Party!” AOC is a reference to Rep. Alexandria Ocasio-Cortez (D-N.Y.), who like Omar is a freshman whom Republicans have sought to cast as among the new leadership of the Democratic Party.

The Congressional Black Caucus Foundation’s Annual Legislative Conference took place Sept. 11-15 in Washington. Adam Green, co-founder of the Progressive Change Campaign Committee, tweeted the video of Omar dancing at one of the CBC events on Sept. 13. The PCCC on Wednesday called the claim that Omar “partied” on the anniversary of the Sept. 11 attacks “an abhorrent lie that endangers a member of Congress.”

“Twitter must remove Trump’s Tweet now,” the organization said.

A spokeswoman for Twitter said it was looking into the matter.

Omar, a freshman Democrat and one of the first Muslim women elected to Congress, has been a frequent target of attacks by Trump and Republicans. After she addressed the Council on American-Islamic Relations in March, Republicans seized on a snippet of her remarks in which she said the Muslim rights organization “was founded after 9/11, because they recognized that some people did something and that all of us were starting to lose access to our civil liberties.”

Trump has also said that Omar and three other minority women in Congress — Ocasio-Cortez and fellow freshman Democratic Reps. Ayanna Pressley (Mass.) and Rashida Tlaib (Mich.) — should “go back and help fix the totally broken and crime infested places from which they came.” Three of the four were born in the United States; Omar was born in Mogadishu, Somalia, and became a U.S. citizen as a teenager.

Williams, the conservative comedian Trump retweeted on Wednesday, has spread conspiracy theories in the past. Last month, Williams suggested that the death of Jeffrey Epstein, who had been facing multiple charges of sex trafficking involving underage girls, might be tied to former president Bill Clinton.

Trump retweeted that claim, as well, and defended Williams as “a very highly respected conservative pundit” with “half a million followers” on Twitter.

In his tweet, sent Monday and retweeted by Trump on Wednesday morning, Williams had shared a clip of Omar dancing and then claimed that she was “partying on the anniversary of 9/11.”

“I need to talk to Omar,” Williams said in the video. “Girl, what in the world were you celebrating on the anniversary of 9/11? ... I need everybody in America to wake up. We have a congresswoman in office that believes that on 9/11, ‘some people just did something,’ and she partied on the anniversary of 9/11. Does this sound American to you?”

Williams concluded the video by suggesting that Omar should “fly your butt back to where you came from.”

Avi Selk contributed to this report.