NEW YORK (AP) — A U.S. Capitol Police officer testified Friday against a New York man accused of threatening to kill members of Congress, recounting how police struggled to quell the “surreal” Jan. 6 riot in Washington.

The defendant, Brendan Hunt, was not part of the siege. But prosecutors in federal court in Brooklyn sought to use the testimony of Special Agent Christopher Desrosiers to frame the episode as a further catalyst for Hunt’s alleged call to massacre members of Congress.

Desrosiers — believed to be the first member of the Capitol force to testify at a criminal trial related to the insurrection — described for the jury how he was assigned to track the mob violence from nearby command center and was shocked to hear radio chatter of his colleagues “yelling for help.”

Asked what he was thinking at time, he said: “For myself, ‘surreal’ comes to mind.”

He testified that his team scrambled to figure out how to evacuate Vice President Mike Pence and lawmakers. But the evacuation was called off when “a sea of backup came and we were able to re-secure the building," he said.

Hunt, 37, an analyst for the New York court system, has pleaded not guilty to charges alleging, in part, that he called for the killings of lawmakers, including Democratic U.S. Reps. Nancy Pelosi and Alexandria Ocasio-Cortez and U.S. Sen. Charles Schumer. Prosecutors say it was part of a monthlong online campaign to urge violence against members of Congress that culminated on Jan. 8 in an 88-second video titled: “Kill your senators. Slaughter them all."

Prosecutors allege Hunt was trying to inspire violence against members of Congress on Inauguration Day as a follow up to the Jan. 6 attack, when hundreds of then-President Donald Trump’s supporters broke into the Capitol and interrupted the certification of Joe Biden’s presidential victory.

Defense attorneys have called the charges overblown and argued that there’s no proof that Hunt was a legitimate threat. One of his lawyers, Jan Rostal, told jurors they could label her client “an idiot or clown,” but the First Amendment blocked his conviction on a criminal charge which could carry a decade in prison.

An FBI agent testified Friday that investigators were concerned that Hunt was plotting to try to obtain guns. But she conceded on cross-examination that they found no evidence he had any direct communications with anyone about getting weapons or staging a another attack.