We begin with gunfire erupting inside a federal courthouse. A defendant shot by U.S. Marshals inside the Salt Lake City court after attacking a witness on the stand. ABC's Clayton Sandell has the... See More
We begin with gunfire erupting inside a federal courthouse. A defendant shot by U.S. Marshals inside the Salt Lake City court after attacking a witness on the stand. ABC's Clayton Sandell has the story. Reporter: The blast of gunfire erupted just as morning court began. Like, boom, boom, boom. And then, boom, boom, boom, boom. Reporter: It happened in a Salt Lake City federal courtroom, packed with spectators, judge and jury, all watching in horror Monday, as 25-year-old defendant, algalau, went from listening from a witness testifying against him, to lunging at that witness. Investigators called it threatening. The defendant may have grabbed a pen or pencil and charged the witness stand. Reporter: A U.S. Marshal opened fire. He was hit several times in the chest. Someone behind us said get on the floor. And everybody dropped. Reporter: He was an accused member of a violent street gang, known for robbery, assault and gun crimes. He was 1 of 17 gang members being prosecuted in a major racketeering case. After the shooting, the judge immediately declared a mistrial. The judge, tainted. But a few hours later, he died. His trial, just beginning, as his own life came to a violent end. For "Good morning America," Clayton Sandell, ABC news, Denver.
This transcript has been automatically generated and may not be 100% accurate.