( CNN ) -- The bomb and gun rampage that left 77 people dead in Norway last summer could have been avoided , an independent report found Monday . Anders Behring Breivik is on trial in the bombing in central Oslo that left eight people dead , followed by a shooting spree at a youth camp on nearby Utoya Island , where 69 people died . `` The police and security services could and should have done more to avert the crisis , '' said Alexandra Bech Gjor , head of the July 22 Commission looking into the attacks . Norway PM : Honor dead by celebrating life . Prime Minister Jens Stoltenberg said after the report was published that he had `` ultimate responsibility for the preparedness in our country , a responsibility I take seriously . '' But he said he would not resign . According to authorities , Breivik set off a fertilizer bomb outside the prime minister 's office on July 22 , 2011 , killing eight people . He then took a ferry to Utoya Island , the site of a Labour Party youth camp , where more than 700 young adults were meeting . Authorities say he roamed the island shooting at campers , killing 69 people before members of an elite Norwegian police unit took him into custody . Experts disagree about whether Breivik was sane at the time of the killings , a critical factor in what sentence he will face . Norway prosecutors want mental institution for Breivik . He does not deny the killings but says they were necessary to protect Norway from multiculturalism . Police could have reacted faster during the attacks , saving lives , the new report found . `` A more rapid police operation was a realistic possibility . The perpetrator could have been stopped earlier on 22 July , '' the investigators concluded . Police operations centers were understaffed , and the availability of helicopters was `` limited , '' the report said . Police forces faced immediate criticism after the attack because they had to travel to Utoya Island by boat rather than helicopter . But the failures of `` leadership and communication '' were more significant than failures of resources , the commission found . Police information-sharing `` is subject to formidable weaknesses , '' and the Police Security Services had not done enough training for a terrorist attack , the commission said . The Oslo bombing itself `` could have been prevented through effective implementation of already adopted security measures , '' the report found . Admitted Norway killer asked to stop fist salutes . It also suggests that police could have been aware of Breivik before the attacks took place , but said there were `` no grounds for contending that the Police Security Service could and should have averted the attacks . '' The report criticizes Norway 's gun controls as `` inadequate , '' even though `` Norway is a country with a large number of weapons . '' And it suggests a failure to understand that one person operating alone `` could cause so much devastation . '' Police are due to respond to the report later Monday . The investigators praised the health and rescue services for their response to the wounded and bereaved , and said government communication with the public was good despite the attack on its headquarters . Norway 's government set up the commission after the attacks , the worst massacre in Norway since World War II . The commission had access to confidential reports , interviewed hundreds of people and got access `` to everything we asked for , '' its report says . Norway 's Breivik gives chilling account of gun massacre . CNN 's Alex Felton and journalist Olav Mellingsaeter contributed to this report .
NEW YORK (AP) — Police had not trained for a terror attack , the investigation found . No one imagined a sole attacker could cause such devastation , the report says . Anders Behring Breivik does not deny killing 77 people in Norway last summer .