A sleeping seven-year-old girl was killed when a Detroit police officer's gun went off during a search for a murder suspect.
Assistant Chief Ralph Godbee said Aiyana Jones was hit in the neck by a single bullet and died in hospital. Police said the girl was sleeping on a couch when she was shot.
"This is any parent's worst nightmare. It also is any police officer's worst nightmare," Mr Godbee said.
Mr Godbee said officers with the department's Special Response Team set off a flash grenade as they entered an apartment with guns drawn about 12.40am local time yesterday, with a warrant to look for a suspect in the murder of a 17-year-old boy.
The lead officer encountered a 46-year-old woman immediately inside the front room of the house and "some level of physical contact" followed, during which the officer's gun went off, Mr Godbee said. The officers had identified themselves as police, he said.
Aiyana's father, Charles Jones, told the Detroit News the woman was his mother and the child's grandmother.
"They came into my house with a flash grenade and a bullet," Mr Jones said. "They say my mother resisted them, that she tried to take an officer's gun.
"My mother had never been in handcuffs in her life. They killed my baby, and I want someone to tell the truth."
Mr Jones told the Detroit Free Press that after hearing the explosive and gunshot, he rushed into the room where his daughter had been sleeping. He said police forced him to lie on the ground with his face in his daughter's blood.
Mr Godbee said the shooting was being investigated and the officer suspended on full pay. Police did not believe the gun was fired intentionally, he said.
The officers had a search warrant and were looking for a 34-year-old man suspected of shooting dead teenager Jarean Blake, who was gunned down on Friday by an off-licence in front of his girlfriend.
Officers arrested the suspect during the search, Mr Godbee said.
Mr Jones said the suspect was not in his apartment but in one upstairs that officers raided at the same time.
Mr Godbee would not comment on newspaper reports that neighbours told police there were children in the house and showed them toys in the front garden.
The Detroit Coalition Against Police Brutality called the girl's death "the pain of pains" and questioned what protocols police used in the raid.
The coalition held a candlelight vigil at the home where she was shot.