Detroit's police chief is calling a shooting that killed a woman just before her 25th birthday a tragic, unfathomable accident. Authorities say an off-duty police officer's gun went off after the woman hugged the officer from behind during a party Sunday. She died later of gunshot wounds to the chest. Police Chief Ralph Godbee told reporters at a news conference Monday that the officer is "very remorseful." Godbee says the gun was in a waist holster made of soft material that would have allowed the trigger to be pulled. He says there's no evidence the officer fired the gun. The chief believes the gun discharged after the woman hugged the officer around his waist. The officer is on desk duty while the case is fully investigated.