The missing 3-year-old girl who was found dead this week in a canal near her northwestern Wisconsin home appeared to have died of accidental drowning, according to preliminary autopsy results revealed Thursday afternoon.

Renna Mae Williams wandered away from her family's home in Danbury sometime before 7 p.m. Tuesday, according to the Burnett County Sheriff's Office.

An autopsy found no signs of foul play, Burnett County Medical Examiner Mike Maloney said.

The girl did have a few scratches on her body, but Maloney said they could have been the result of her falling into the water.

"It's very, very tragic," Maloney said.

Final results from a toxicology test will take four to six weeks, he said.

Authorities were draining the canal Thursday as part of the investigation.

Divers found the girl's body about 4:50 p.m. Wednesday after an extensive search, said Rhonda Reynolds, the county's emergency management director. Officials did not reveal that they had found her body until they had notified her family.

The initial search by law enforcement included rescue personnel, police dogs and a Minnesota State Patrol helicopter with an infrared imaging system.

More than 500 people, including hundreds of volunteers, searched for Renna throughout the day, Reynolds said.

Searchers scoured an area along the Yellow River south of Danbury, Reynolds said. Part of the search area also had included the St. Croix River and the Minerva dam, county spokeswoman Dawn Sargent said.

Both parents were home when the girl wandered away, Sargent added.

Nicole Norfleet • 612-673-4495; Twitter: @stribnorfleet