Updated

A North Dakota man was charged Thursday with three counts of first-degree intentional homicide in the deaths of his three young daughters in northwestern Wisconsin.

Aaron Schaffhausen, 34, was being held in jail Thursday, city administrator Scot Simpson said.

Police discovered the bodies of 11-year-old Amara Schaffhausen, 8-year-old Sophie Schaffhausen and 5-year-old Cecilia Schaffhausen in the home they shared with their mother in River Falls on Tuesday.

The man contacted their mother Tuesday, asking to stop by for a visit. He later called her to say he had hurt the girls, police said Wednesday, and, soon after, authorities found their bodies in the River Falls home.

Police are still investigating exactly how the girls died and what might have led up to the killings.

More On This...

"It's certainly the worst that we've seen," police River Falls Police Chief Roger Leque said of the crime.

Police have not said whether or not Schaffhausen has made a confession in the killings, but previous claims of harassment and threats have begun to surface.

Aaron Schaffhausen and his wife, Jessica, divorced in January, Fox 9 reported. The papers were filed jointly, but there are a few signs that the dissolution of the marriage didn't spell the end of trouble for the couple.

"River Falls police records indicate there was a domestic incident in August 2009 at the Morningside residence, and a March 2012 harassment incident where the father allegedly threatened to harm at least one of the children," Leque confirmed

They were awarded joint legal custody of the girls, although Jessica Schaffhausen had primary physical custody and had control over health care, education and other decisions.

Leque said during a news conference Wednesday that Aaron Schaffhausen lived in Minot, N.D. He contacted his ex-wife on Tuesday and asked for an unplanned visit with the girls.

Jessica Schaffhausen, who wasn't home, agreed. Her ex-husband arrived at the River Falls home the girls shared with their mother, and when he arrived, the girls' baby sitter left, Leque said.

Sometime later, Aaron Schaffhausen called his ex-wife and told her he had "harmed" the children, as Leque put it. She, in turn, called police while driving home.

Police arrived to find the gas fireplace on the home's first floor was turned on, Leque said. They smelled what Leque described as a flammable liquid in the basement, but the chief did not say what it was or how it got there. It's unclear what role, if any, the liquid may have played in the deaths — police are still waiting for the children's autopsy reports.

A source told Fox 9 that the girls had suffered serious physical harm.

Leque did not elaborate when asked if there were signs of a struggle, saying authorities were still processing the crime scene.

It's also unclear what may have led up to the incident. Leque said police were called to the house in 2009 for a domestic incident, but he didn't have any details. Leque said police records also show what he called a "harassment incident" in March 2012, in which the father threatened to harm at least one of the girls. Leque said police were unaware of any restraining or protection order.

Schaffhausen turned himself in Tuesday afternoon after the girls' bodies were found. Leque described his demeanor as "non-talkative." It was not immediately clear whether Schaffhausen had an attorney.

The house is located in a newer subdivision on the east side of River Falls, a city of 15,000 about 30 miles east of Minneapolis-St. Paul. On Wednesday morning, police had blocked off the streets surrounding the house with tape and barricades.

Neighbor Heather Johnson said the girls were happy, sweet girls who played with her 8-year-old son, Blake Patrow. She said Amara liked to skateboard and play soccer, and Sophie participated in martial arts and Girl Scouts.

She said Blake and Sophie were in the same elementary school class, and Blake has been clingy and doesn't want to sleep alone after learning his friends are gone.

"He doesn't like that he's not going to see his friends anymore," she said.

Grief counselors were called to Greenwood Elementary School, where the older girls attended and the youngest was scheduled to start kindergarten this fall. The school set aside some time to help families and students deal with the loss.

"These girls were bright girls ... with a zest for life," said principal Nate Schurman. "They left a mark on our school."

A Facebook page had been set up to honor the girls. A vigil was planned for Wednesday night at a local park.

Click for more from myFOXtwincities.com.

The Associated Press contributed to this report.