(CNN) -- A mental health evaluation has been ordered for a Maryland mother accused of stabbing two of her children to death and wounding two others while attempting an exorcism, authorities said Tuesday.
A judge ordered Zakieya L. Avery, 28, and another woman, 21-year-old Monifa Sanford, to undergo the evaluations this week to determine whether they are competent to stand trial, Capt. Marcus Jones of the Montgomery County Police Department said.
Avery and Sanford have both been charged with two counts of first-degree murder and two counts of attempted first-degree murder in connection with the stabbings at a Germantown residence.
Norell Harris, 1, and his sister, Zyana Harris, 2, suffered fatal stab wounds while their siblings, ages 5 and 8, were hospitalized with injuries, authorities said.
Police said they found the four children Friday morning after a neighbor called 911 to report suspicious activity at the home. The neighbor reported seeing a car with a door open and a knife next to it.
Investigators believe the two women were performing an exorcism, a ritual aimed at defeating purported evil spirits or demons.
Avery, according to Jones, allegedly formed a group called "Demon Assassins" because she believed that by doing so evil wouldn't take over their lives.
"The purpose was to get rid of the devil, the evil spirits," Jones said.
Police are searching for two men who are believed to also have been members of the group, he said.
Sanford's attorney, Edward Leyden, said he has no information regarding the allegations that his client was a member of the exorcism group.
"This tragedy is a universal one," Leyden said. "...The family of the victims is devastated, and all the members of Ms. Sanford's family are devastated."
Leyden said he want his client to undergo the mental health evaluation to determine issues of competency and mental delusions.
Avery's attorney did not immediately respond to a CNN request for comment.
Police were initially called to the home Thursday over reports of an unattended child in a car. By the time they got there, the child was not in the car and no one came to the door, authorities said.
After the neighbor's call, authorities notified county child protective services and asked them to follow up. It's unclear whether they did.
Both women are being held without bond.
CNN's Chelsea J. Carter contributed to this report.