New York City police have still not found the woman who kidnapped her eight children from a child agency during a supervised visit on Monday.

According to police, 28-year-old mother Shanel Nadal was routinely visiting her children on Monday afternoon at a child welfare agency in Queens when she walked out of the building with her children.

Seven of the children, who range in age from 11 months to 11-years-old, are boys who all share the same as their biological father, 34-year-old Nephra Payne, though they all have different middle names. The eighth child, a baby girl named Nefertiti, is the youngest.

Authorities said Nadal might be travelling with Payne and possibly the children in a black Chevrolet Suburban, Ford sedan or black Infiniti, according to the Associated Press.

The NYC Administration for Children's Services launched an investigation immediately after the kidnapping to determine how this incident could have occurred during a supervised visit. During supervised visits, an agency staff member should be present at all times while still affording the family personal time together, according to spokesman Michael Fagan.

The Wall Street Journal reported that Nadal was reported to authorities in 2009 when the oldest child at the time, who was 8-years-old, went to school sporting a black eye. After the child said it was a result of abuse from his father, an investigation found that the other five children were abused as well, leading to her custody loss. It is uncertain if Nephra Payne's 2009 arrest for assault was related.

According to ABC, Children's Services have received arrest warrants for both Shanel Nadal and Nephra Payne.