Three teenagers threw stones at Anders Breivik as he shot dead 69 people at an island youth camp in Norway, according to a report Monday.
Citing Norway’s Dagbladet newspaper, the news website RT.com said one of the youths was shot dead, prompting the other two to flee.
The report said that Breivik, 32, who has confessed to the killings, swore at them after one stone hit him on the head.
Movsar Zyamaev, 17, and Rustam Daudov, 16, originally from Chechnya, survived the attack. The teenager who died was not named in the report.PhotoBlog: Norway killer reconstructs shooting spree for police
The report said they had originally thought the attack was some kind of joke, but realized it was serious when they saw Breivik shoot three people dead, including a friend.
They fled to the woods, where Movsar telephoned his father, who told him to try to stop Breivik if he could and to stay calm and help other people.
After throwing stones at Breivik, the report said they gathered a group of survivors in a hiding place near the shoreline.
Movsar pulled three people from the water, deciding it was too cold to try to swim to safety.
Breivik returns to island
The report emerged after Breivik was taken back to the island Saturday.
Held tightly on a police leash, he took part in a reconstruction of his actions on July 22 for police.
In a photograph of the visit carried by the VG newspaper, Breivik is shown standing in a shooting position, as if aiming a rifle at someone in the water trying to swim away.
The killings on the island happened after Breivik killed eight people in the capital Oslo with a bomb.
On the island, Breivik described the killings in close detail during an eight-hour tour with 10-12 police, prosecutor Paal-Fredrik Hjort Kraby told a press conference in Oslo.
The hearing took place amid a massive security operation that aimed to avoid escape attempts by Breivik and protect him against potential avengers.
"We were able to animate his memory with regard to what happened out there," police prosecutor Paal-Fredrik Hjort Kraby told reporters Sunday, adding that "many new details" emerged in the eight-hour journey around the island Saturday.
"The suspect showed he wasn't emotionally unaffected by being back at Utoya ... but didn't show any remorse," Kraby said.
"He has been questioned for around 50 hours about this, and he has always been calm, detailed and collaborative, and that was also the case on Utoya," he said.Story: Insanity ruling not likely in Norway
Breivik walked roughly the same route as the one he took during the shooting spree and explained what happened with as little interference as possible from police, Hjort Kraby said.
The entire hearing was filmed by police and will later be used in court, he added.
Images of the reconstruction published in the Norwegian daily VG show Breivik simulating shots into the water, where panicked teenagers tried to escape from him.
It had been arranged to avoid the need for a reconstruction in the midst of the trial and to make the suspect remember more details, Hjort Kraby said.
The prosecutor also confirmed Norwegian media reports that police received several phone calls from Breivik himself during the terror attack, but wouldn't say how police had reacted to the calls.
According to Norwegian daily Aftenposten, Breivik offered to surrender several times and asked police to call him back, but they didn't.
Breivik's lawyer has said he has admitted to the terror attacks, but denies criminal guilt because he believes the massacre was necessary to save Norway and Europe from Muslims and punish politicians who have embraced multiculturalism.
Breivik faces up to 21 years in prison if he is convicted on terrorism charges, but an alternative custody arrangement — if he is still considered a danger to the public — could keep him behind bars indefinitely.
The Associated Press and Reuters contributed to this report.