McManus said that the father of the children had been trying to get in contact with the mother before he visited their apartment.
The mother was later identified by the Bexar County Medical Examiner's Office as 38-year-old Karina Kleberovna Sornoza Deitering, according to the San Antonio Express-News.
"According to the father, she had lost custody of the children very, very, very recently and this was the terrible end results of that. Tragic beyond words. Two little children, a grandmother, and a mother," McManus said.
It is unclear why the 38-year-old woman lost custody of her children, as the father of the children said that Sornoza Deitering had no history of violence.
Police are currently trying to figure when the crime happened.
According to the police, the motive behind the crime is not clear, as they're trying to find out what led to the incident.
McManus said he doesn't believe there is a connection between the shooting and the stress caused by the ongoing pandemic.
Police officers at the scene of the crime have interviewed the neighbors regarding the gunshots.
One of the neighbors living at the apartment complex, Ed Gardner, said that he's seen the children playing outside during the lockdown order, according to San Antonio Express-News.
"It's crazy that you're going to hurt your own kids. They looked up to you to protect them. Not kill them, and then your mother. Just crazy. It's just crazy," Gardner said.