Updated

A 13-year-old girl reported missing Thursday has been found dead in a park in the Northern California city of Fairfield, police said.

A passer-by discovered the girl's naked body a little before 7 a.m. Friday in the city's Alan Witt Park and flagged down a police officer who was driving by, Fairfield Police Officer Cleo Mayoral said Saturday.

The girl was reported missing around 5:45 p.m. Thursday after she had left a foster home in nearby Suisun City, Mayoral said. Her name was not released.

An autopsy was performed, but Mayoral said officials weren't releasing the results. He did say that when the girl's body was found there were no obvious signs of trauma.

No suspect or suspects have been identified, but detectives were canvassing neighborhoods and checking video images from surveillance cameras as part of their investigation, Mayoral said.

"We have all our resources working on this," Mayoral said. "All our detectives, our crime scene people, our criminologists and our patrol division."

He added investigators were trying to track the girl's activities in the hours before she ended up in Alan Witt Park.

Sacramento television station CBS13 reported the girl attended Green Valley Middle School, which is about eight miles from the park.

School Principal Gregg Hubbs declined to comment on the girl's death, and Fairfield police couldn't say if she had attended school on the day she was reported missing. Fairfield police referred questions about the scope of the investigation to the Suisun City Police Department, which did not return repeated calls from The Associated Press seeking details on the case.