Police said communication flaws and other mishaps slowed down their response to the youth camp shooting massacre that left 69 people dead last July.
They pointed to the breakdown of an overloaded boat that was carrying SWAT officers to the island where dozens of youth campers were shot and killed. Police also said a helicopter should have been called in sooner.
The confessed gunman, Anders Behring Breivik, is accused of setting off a bomb that killed eight people in Oslo before going on the shooting rampage. He was arrested 1 hour and 20 minutes later, according to an indictment presented last week.
The Associated Press contributed to this report.