Lillie Robbins, a juror in another case, said she had just passed the courthouse security checkpoint when she saw a group of officers pursuing the suspect. "All of these deputy sheriffs broke out of the elevator an a dead run," she said. "They were yelling, 'Get out, get out, get out of the building!'"

The shooting immediately raised questions about security procedures in the courthouse, in part because Mr. Nichols, 6-foot-1 and 200 pounds, had been caught with two handmade knives in his shoe just two days ago, and in part because he was apparently being escorted by only one deputy. The shooting also comes at a time of increased attention to the safety of jurists, heightened by the killing of a federal judge's husband and mother in Chicago last week by a man, investigators say, who had a case in that judge's court. That suspect later committed suicide.

About 9 a.m., Mr. Nichols, who was not free on bail, was taken from a detention room in one part of the courthouse to a small room on the eighth floor so that he could change into street clothes before going into the courtroom, on the same floor but in the older wing of the building, a court official said. He was escorted by Deputy Hall, according to Assistant Chief Alan Dreher of the Atlanta Police Department. Defendants in Fulton County, as in many jurisdictions, do not appear in the courtroom in jail uniforms or handcuffs to avoid prejudicing the jury, but Chief Dreher said investigators were not yet sure when Mr. Nichols's handcuffs had been removed or exactly where the struggle over the gun began.

After beating up Deputy Hall and taking her gun, "the suspect then made his way into the courtroom and held all of the persons inside at bay with a handgun," Chief Dreher said at a news conference on the steps of City Hall. "He then shot and killed the judge, shot and killed the court stenographer, and made his escape from the courtroom."

Deputy Hall, described as a 16-year veteran, was left with a gashed forehead, facial fractures and a bruise to her brain, according to a trauma surgeon at Grady Memorial Hospital, where she was treated.