Chanty Mao has been charged with stabbing her two children, 12-year-old Sorvanna and 8-year-old Sorvan, to death in their South 18th Street home.
It was shortly after 5:00 p.m. Wednesday when officers were called to the home on the 1700 block of South 18th Street.
Authorities arrived to find the bodies of both children in a first floor apartment bedroom.
Police say the two were stabbed multiple times in their chests with a kitchen knife.
"I went to the scene, obviously it was a bad scene. Anytime you have children that are murdered, it's worse than your typical homicide, quite frankly. To have it happen at the hands of a parent makes it even more tragic," Philadelphia Police Commissioner Charles Ramsey said.
Responding officers say Mao's behavior was bizarre and erratic. Police explain Mao had been undergoing psychiatric treatment for several years.
"Family members thought she may have ingested pills. I don't know if that turned out to be true or not, but as a precaution we took her to the hospital," Ramsey said.
"It's not her fault, I know it's not her fault, she did not mean to do that," Chanthy Mao's sister Chan told Action News.
Chan Mao says her sister is bipolar and on medication.
Only Action News was there overnight the 27-year-old mother was escorted by police from the Hospital of the University of Pennsylvania where she was taken for evaluation.
Chan says last night her sister wrote a suicide letter stating she loved her children so much, she wanted to take them with her.
"My niece and my nephew are the best things in my life I ever had, they are very well behaved and very smart," Chan said.
Action News has learned Chanty Mao emigrated from Cambodia four years followed by her two children a year ago; they moved into the apartment with her parents.
The children's uncle, Nimol Mao, says he always told them they would have a great future.
"Do good on SATs, get a scholarship, go to good school, get a good job," Nimol Mao said.
The family says Sorvanna and Sorvan were very close and they both loved to dance as the home movies show.
"It's just too short to take them away from us," Chan said.
Family members say Chanty Mao never hurt her kids before.
Funeral arrangements for the two children are still being made.