Federal law enforcement officials are examining threats aimed at members of Congress as the second impeachment trial of former President Donald Trump nears, including chatter about killing legislators or attacking them outside the U.S. Capitol, an official told The Associated Press on Sunday.

The threats, and concerns that armed protesters could return to sack the Capitol anew,  prompted the Capitol Police and other federal law enforcement to insist thousands of National Guard troops remain in Washington as the Senate moves forward with Trump’s trial, said the official, who was not authorized to discuss the investigation publicly and spoke on condition of anonymity.

Read more: USA Today