Tens of thousands of Norwegians have gathered in Oslo to sing a folk song about multiculturalism, while confessed killer Anders Behring Breivik sat in court, hearing the testimony of survivors of his attacks last July at a government building and a political youth camp.

Breivik admits to killing 77 people in order to fight multiculturalism in Norway and what he sees as a Muslim invasion of Europe.

The demonstrators waved roses and flags Thursday as they and Norwegian folk singer Lillebjoern Nilsen sang an adaptation of the children's song, “My Rainbow Race,” which Breivik in court last week called an example of Marxist brainwashing.

Members of the crowd later marched to the courthouse. Inside, a 24-year-old woman described how she fell into a coma and lost her memory after Breivik detonated a bomb at the government building where she worked. A man who worked in the same building described how he had lost 80 percent of his sight as a result of the blast, which killed eight people.

On Wednesday, Breivik told the Oslo court that a report declaring him insane was based on “fabrications” by court appointed psychiatrists. He has previously said an insanity ruling would be “worse than death.”

Last week, Breivik described in chilling detail how he hunted down and shot to death 69 people last July at a political youth camp on an island outside Oslo.

He told a court filled with relatives of those he killed that at first he was hesitant to carry out his plan to shoot as many people as he could when he arrived on Utoya island. But he said the killing became easier once he shot his first victim in the head.

Breivik had already killed eight people by setting off a bomb at a government building in Oslo.

Breivik said he planned the bombing of that building after intensively researching other attacks throughout the world, including that of another anti-government terrorist, Timothy McVeigh, in the United States. McVeigh, who has since been executed, planted a truck bomb in Oklahoma City in 1995 that killed 168 people and injured more than 600.

Norway does not have the death penalty, but if the court finds him guilty and sane, he will serve a maximum 21-year sentence, which could be extended if he were considered a continued danger.