Utoya massacre

Approximately one and a half hours after the Oslo explosion, a man wearing a police uniform, confirmed to be Anders Behring Breivik, boarded a ferry at Tyrifjorden, a lake some 40 kilometres (25 miles) northwest of Oslo, to the island of Utøya, the location of the Norwegian Labour Party's annual AUF youth summer camp, which is organised there every summer and which was attended by approximately 600 teenagers.

Former prime minister Gro Harlem Brundtland, whom Breivik said he hated and referred to in his writings as "the murderer of the nation, had been on the island earlier in the day to give a speech to the camp. After the attack Breivik stated that he originally wanted to target her especially; but because of delays related to the ongoing renovation of Oslo Central railway station, she was already gone when the shooting started.

When Breivik arrived on the island, he presented himself as a police officer who had come over for a routine check following the bombing event in Oslo. He signalled and asked people to gather around him before pulling weapons and ammunition from a bag and indiscriminately firing his weapons, killing and wounding numerous people. He first shot people on the island and later started shooting at people who were trying to escape by swimming across the lake. Survivors on the island described a scene of terror. In one example, 21-year-old survivor Dana Berzingi described how several victims wounded by Breivik pretended to be dead to survive; but he later came by to shoot them again in the head with a shotgun.[61] He did relent in his executions on two occasions: First, when an 11-year-old boy who had just lost his father during the shooting, stood up against him and said he was too young to die; and later, when a 22-year-old male begged for his life.[65]

A spokesman for the National Police Directorate under the Ministry of Justice and the Police reported that most of the casualties were youths about 15 or 16 years old. Trond Berntsen, an off-duty, unarmed police officer and step-brother of Norway's crown princess Mette-Marit, was among the dead. Some witnesses on the island were reported to have hidden in the undergrowth, and in lavatories, communicating by text message to avoid giving their positions away to the gunman. The mass shooting reportedly lasted for around an hour and a half, ending when a police special task force arrived and the gunman surrendered, despite having ammunition left, at 18:35. It is also reported that the shooter used hollow-point or frangible bullets (dum-dums) which increase tissue damage.

Local residents in a flotilla of little motorboats and fishing dinghies bravely sailed out to rescue the survivors who were pulled out shivering and bleeding from the water and picked up from hiding places in the bushes and behind rocks around the island's shoreline. Some survived by pretending to be dead. 47 of the campers sought refuge in Skolestua ("the School House") together with personnel from the Norwegian People's Aid. Although Breivik shot two bullets through the door, he did not get through the locked door, and the people inside this building survived.