NEW : The prime minister says he will not hand over the weapon . Police had not trained for a terrorist attack , the investigation found . No one imagined a sole weapon could cause such devastation , the report says . Anders Erik Breivik does not deny killing 77 people in Norway last year .
NEW : The prime minister says he will not resign over the report . 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 .