A fire that killed a Missouri mother and four children was intentionally set by the mother, police said.

St. Louis County police announced late Wednesday that a preliminary investigation ruled that the deaths of Bernadine "Birdie" Pruessner, her twin 9-year-old daughters Ivy and Lillie Pruessner, and her children 5-year-old Jackson Spader and 2-year-old Millie Spader was a murder-suicide.

Police Sgt. Tracy Panus said in an email that investigators believe that Bernadine Pruessner, 39, set fire to a mattress. "A note was also left stating Bernadine’s intentions to take her life and the lives of her children," Panus said. No other details of the investigation have been released.

House Fire Virginia

Firefighters gather around a burned out section of a home after they extinguished the flames of house fire on Monday, Feb. 19, 2024 in Ferguson, Mo. A mother and four children died early Monday as police say the fire is being investigated as "suspicious." (David Carson/St. Louis Post-Dispatch via AP)

7 OF 9 LOS ANGELES FIREFIGHTERS OUT OF HOSPITAL AFTER TRUCK BLAST

Responding firefighters found the home in Ferguson engulfed in flames at 4:23 a.m. Monday. Neighbors had tried to save the family, but the fire was too intense.

Pruessner and the fathers of the children were involved in prolonged legal disputes over the kids, according to a statement issued on behalf of her relatives by her attorney, Nathan Cohen. She had been happy and enjoyed life and was a loving mother, but those court battles brought her to a moment of crisis, the statement said.

"Birdie got to an awful place, one that resulted in tragic consequences," the statement said.

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KSDK-TV reported that the two fathers also released a joint statement.

"As dads, right now we have to focus on honoring the four beautiful lives, and we plan to do that together," they said. "Our thanks go out to the community, people we know and many we have never even met, who have shown us incredible amounts of support. We will continue to need it."