Jan. 19, 2014 -- Two women charged with stabbing and killing two children in Germantown, Md., believed they were performing an exorcism, Montgomery County Police said.
Police charged both Monifa Denise Sanford, 21, and the mother, Zakieya Latrice Avery, 28, with two counts of first degree murder and two counts of attempted first degree murder.
"Investigators have learned that the two defendants believed that they were performing an exorcism," police said in a statement released Saturday.
On Friday around 9:30 a.m., police responded to a call at a townhouse where officers discovered what they described as a "very bloody" crime scene.
Police found both Norell Harris, 1, and Zyana Harris, 2, dead with multiple stab wounds. Avery's two other children, Taniya Harris, 5, and Martello Harris, 8, along with Sanford were also found injured and taken to a hospital.
Avery was unhurt. Police arrested the woman when she attempted to flee the scene. She was being held without bond.
Taniya Harris and Martello Harris remain hospitalized, while Sanford was arrested this afternoon following her release from hospital, police said in a statement.
"Cases like this are heartbreaking" Montgomery County Police Chief Tom Manger said in the statement. "Our thoughts are with the family and friends of the victims along with the 911 operators, police officers, evidence technicians, and fire and EMS personnel that responded."
The turmoil began Thursday night, when police responded to a 911 call by a neighbor reporting a child left unattended in a vehicle, Montgomery County Police Captain Jim Daly told ABC News.
By the time police arrived, two women left the townhouse, retrieved the child, and re-entered the home. Police investigated and arranged for child protective services to visit the home of the child.
On Friday morning, police received another 911 call from a resident of the same neighborhood reporting blood on the outside of a vehicle and a knife lying outside of the vehicle, prompting police to enter the residence. When they entered, Avery allegedly fled out of the back of the home and was apprehended by police, authorities said.
Police found two children dead in the upstairs part of the home, as well as the two other children and Sanford, who suffered injuries. Sanford is not believed to be a family member but is believed to have lived at the residence, police said.
ABC News' attempts to locate attorneys for the two accused women were unsuccessful.
ABC News' Jack Cloherty, Tom Giusto and Colleen Curry and The Associated Press contributed to this report.