OSLO, Norway - The trial of Anders Behring Breivik was interrupted briefly Friday when the brother of one of his 77 victims hurled a shoe at the confessed mass killer and yelled, "Go to hell," before being escorted from the court room, police and witnesses said.

It was the first outburst from the normally subdued crowd watching the terror trial in Oslo's district court since the proceedings began in mid-April.

Breivik - a self-styled anti-Muslim militant - has been charged with terrorism, admitting he carried out a bomb-and-shooting rampage that stunned Norway on July 22.

On Friday, forensic experts were going through autopsy reports for some of the 69 victims killed in the shooting massacre at a youth camp that day, when a man in the second row suddenly stood up, said Mikaela Akerman, a Swedish journalist who was in the court room.

"He threw one of his shoes at the desk where Breivik sits with his defence lawyers," Akerman told The Associated Press. He shouted, 'You killer, go to hell.' And repeated it several times."

The shoe hit one of Breivik's defence lawyers but she was not hurt. Breivik remained calm and "smiled a little" as he watched security guards apprehend the man and lead him out of the court room, Akerman said.

"He keeps shouting and is crying heavily as he's being led out," Akerman said. "Some of the spectators clapped their hands. Some yelled 'Bravo.' Many others started crying."

Breivik addressed the court as proceedings resumed after a 10-minute break. "If someone wants to throw something at me, you can do it when I walk in or when I leave, thank you," he said, according to Akerman.

Throwing of shoes to insult someone has long been a form of protest in many countries, but the practice gained widespread attention when an Iraqi threw his shoes at then-U.S. President George W. Bush at a televised news conference in Baghdad in 2008 during the Iraq war.

Police didn't identify the shoe-thrower in Oslo but said he was the brother of one of the victims.

Police operations leader Rune Bjoersvik downplayed the outburst, calling it a "spontaneous and emotional reaction" that didn't pose a "serious security risk."

The man was emotionally distressed and was taken away from the court in an ambulance, Bjoersvik said.

The incident offered a sharp break with the polite atmosphere that has reigned inside the courtroom, even as Breivik testified in graphic detail on how he set off a car bomb that killed eight people in Oslo's government district and then hunted down teenagers at the Labor Party's annual youth camp on Utoya island.

The far-right fanatic has admitted to the attacks but pleaded innocent to terror charges, saying the victims were traitors for embracing multiculturalism.

Psychiatrists have reached conflicting conclusions about Breivik's mental state -- the key issue to be resolved during the trial. If found guilty and criminally sane, he would face 21 years in prison, though he could be held longer if deemed dangerous to society. If declared insane, he would be committed to compulsory psychiatric care.

Police didn't say how the shoe-throwing incident would affect their security procedures at the court. As the trial resumed later Friday, three security guards were placed at the front of the gallery.

Frode Elgesem, a lawyer for the bereaved, said he didn't consider the incident as a violent attack.

"I experienced this outburst as a desperate expression of despair," he told Norway's NTB news agency.

The defence lawyer who was hit by the shoe, Vibeke Hein Baere, told national broadcaster NRK she hoped the incident would not be repeated during the trial, which is scheduled to end in late June.

"There are many weeks left and I hope and believe that we will return to the dignified manners we have seen up until now," she said.