All the bodies were found in a ground floor apartment, and investigators have reportedly ruled out carbon monoxide poisoning
Both suspects are set to be charged with five counts of homicide and one count of conspiracy
A mum and daughter allegedly killed five members of their family - including two nine-year-old twins - in a horrific attack.
The killings happened in Morrisville, Pennsylvania, with two nine-year-old twins among the dead.
It is not yet known how the victims were killed.
Shana Decree, 45, and daughter Dominique Decree, 19, have been charged with the murders.
The victims are Shana's daughter Naaâ€™Irah Smith, 25, son Damon Decree Jr, 13, her sister Jamilla Campbell, 42, and Campbellâ€™s twin daughters Imani and Erika Allen, both nine.
Police have appealed for information about Campbell's son Joshua, 17, but said he is not a suspect.
Five bodies were found inside the home, while two were found alive, and were taken to hospital.
According to reports in the US, the victims had no obvious injuries.
Worried neighbours had contacted police as none of the family had been seen since Friday.
Bucks County District Attorney Matthew Weintraub said: "This is a terrible tragedy.
"I just spoke with the family of all five of the deceased and we're all heartbroken."
He told theÂ Bucks County Courier Times: "The people that committed these atrocious acts are in custody and weâ€™ll make them pay for their crimes.â€
Both suspects are set to be charged with five counts of homicide and one count of conspiracy.
One of them was having seizures when she was taken to hospital, according to reports.
All the bodies were found in a ground floor apartment, and investigators have reportedly ruled out carbon monoxide poisoning.
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