New Bedford Police and State Police detectives are investigating the death of a baby girl in the city.

According to the Bristol County District Attorney's Office, 9-month-old Ariel Eluziario was brought to St. Luke's Hospital around 6pm last night. She was then flown to Hasbro Children's Hospital in Providence where she was pronounced dead just after 10pm Thursday.

Prosecutors this morning have charged 21-year-old Ethen Harrison of New Bedford with reckless endangerment of a child, assault and battery on a child causing substantial bodily injury, and assault and battery with a dangerous weapon.

Harrison lives with the deceased infant's mother, 22-year-old Amanda Eluziario, but is not the child's biological father.

An autopsy is being performed to determine the exact cause of death.

Harrison is being arraigned today in New Bedford District Court.

Update 5:12pm - New Bedford district court judge Bernadette Sabra ordered Harrison held without bail on Friday. Prosecutors say Harrison admitted to 'certain acts' that were consistent with injuries sustained by the infant.

According to court documents, Harrison admitted to police the baby became "fussy", and he dropped the child on the floor, causing her to hit her head. Harrison said he then forcefully picked the infant up, snapping her head forward.

Harrison then threw the baby onto the bed so hard the child bounced off and fell 4 feet to the floor, once again hitting her head. Harrison says he then slapped the baby several times across the face and the side of her head.

The State Medical Examiner's Office is expected to conduct an autopsy later Friday. Prosecutors said the charges against Harrison could be upgraded to murder.