Shana S. Decree, 45, and Dominique Decree, 19, were charged with five counts of homicide and one count each of conspiracy.
Shana Decree told police that "everyone at the apartment ... wanted to die" and talked about suicide, according to court documents. Decree claimed one of the victims, Jamilla Campbell, 42, killed two other victims before she herself was slain.
The bodies were found Monday inside an apartment in suburban Philadelphia after Bucks County child welfare officials showed up unannounced and got no response when they knocked on the door. A maintenance worker opened the door and found Shana Decree and Dominique Decree in a "disoriented" state, according to court documents.
Police arrived and found all five bodies in a bedroom. The apartment was in "disarray," according to Police Chief George McClay, with broken drywall and broken glass, overturned furniture, and other clutter.
Shana Decree was arraigned early Tuesday, while her daughter was expected to make her initial court appearance later in the day.
It wasn't clear whether either woman yet has a lawyer to speak for her.
The victims included Shana Decree's children Naa'Irah Smith, 25, and Damon Decree Jr., 13, both of Morrisville; as well as Shana Decree's sister Jamilla Campbell, of Trenton, New Jersey, and Campbell's 9-year-old twin daughters Imani and Erika Allen. Authorities did not reveal how they died.
Bucks County District Attorney Matthew Weintraub said that authorities were looking for Campbell's 17-year-old son Joshua. He stressed the teen is not a suspect, adding authorities just want to "ensure his safety."
"We wanted to come out here at this point and make sure that everybody knew that the people that committed these atrocious acts are now in custody and will be made to pay for their crimes," Weintraub said at the scene late Monday.
The bodies were found about 4 p.m. Monday after police went to check on the welfare of residents at the unit in the Robert Morris Apartments in Morrisville, along the border with New Jersey about 30 miles (50 kilometers) northeast of Philadelphia.
The three-story, red-brick complex is on a busy road lined with auto repair shops, a safe-and-lock shop and a bail bonds agency nearby.