SALT LAKE CITY

- Defendant Siale Angilau was listening to a witness describe gang initiation rituals yesterday when authorities said he grabbed a pen, rushed toward the witness and lunged at him.

A U.S. marshal opened fire on Angilau - a 25-year-old "Tongan Crip" gang member known on the street as "C-Down" - shooting him several times in front of shocked jurors, lawyers and courtroom watchers. He died hours later.

The shooting turned a new and secure federal courthouse that opened its doors just one week ago into a site of terror and alarm. Nobody else was hurt, but those in the courtroom were stunned by the sudden turn of events. A mistrial was declared, with U.S. District Judge Tena Campbell saying in her order that jurors were visibly shaken and upset.

"It was kind of traumatizing," said Sara Jacobson, who was in the courtroom to support her grandmother, who was scheduled to testify in Angilau's trial.

Her father, Perry Cardwell, was with her and said Angilau was shot at least six times as he attacked the witness, who collapsed to the ground. As he recounted the scene, Cardwell said he remembers hearing somebody yell to get down.

The witness, who was not injured, appeared to be in his mid-20s and was testifying about gang initiation, Cardwell said. The person was not identified.

Angilau was shot in the chest and died at a hospital, the FBI said in a news release. Under standard procedures, Angilau was not restrained in the courtroom, the FBI said.

He was shot after acting in "an aggressive and threatening manner," the agency said.

Angilau was one of 17 people named in a 29-count racketeering indictment filed in 2010 accusing gang members of assault, conspiracy, robbery and weapons offenses.