WASHINGTON — Danielle and Alexander Meitiv, the Maryland parents who have been criticized by Child Protective Services for letting their 10- and 6-year-old children walk and play in their suburban D.C. neighborhood alone, are now filing a lawsuit.

This comes after the children’s latest encounter with CPS, which took place Sunday. Local police say they received a call to check the welfare of two kids in the area of Fenton and Easley Streets in Silver Spring around 5 p.m.

Rafi, 10, and Dvora, 6, were found in a parking garage in that area, police say. The responding officer then contacted CPS. Under Maryland law, police officers who become aware of circumstances involving possible child abuse or neglect are mandated to contact representatives of Child Protective Services.

Around 7:20 p.m., a decision was made to transport the children to the CPS offices in Rockville. The officer was also advised that CPS would notify the parents. Police say the officer followed the direction of the CPS worker as procedures dictate – due to the serious nature of a Child Protective Services investigation and concern for the welfare of the children, they cannot be returned home until their safety can be assured.

Police say the officer and children arrived at CPS at approximately 7:45 p.m.

A news release from the Meitiv family’s legal representation, Wiley Rein LLP, says the kids “were subjected to a terrifying detainment that no child should have to experience,” despite being “three short blocks from their home.”

The Meitivs dropped the kids off at the park so they could play after a six-hour drive back from upstate New York, telling them to be home by 6 p.m., they say.

The law firm release goes on to claim that Danielle and Alexander Meitiv were not contacted by police Sunday and that Rafi and Dvora were not allowed to call them, despite the fact that the children told police that they knew their address and would like to call home.

The kids “were confined to the back of a police car for almost three hours without any explanation of why they were being detained,” and they did not have any food and only limited access to the bathroom during that time.

Police say the officer who picked the kids up had his personal lunch with him and was going to give it to the children when the older child advised that he and his sister had food allergies. The officer says he did not want to provide any food items that might cause an adverse reaction.

The children also did not return home until 11 p.m. despite having school the next morning, according to the family.

“The Meitivs are rightfully outraged by the irresponsible actions of Maryland CPS and Montgomery County Police,” says Matthew Dowd, a partner with Wiley Rein.

“We must ask ourselves how we reached the point where a parent’s biggest fear is that government officials will literally seize our children off the streets as they walk in our neighborhoods.”

Dowd goes on to say that the actions of CPS “are premised on a fundamental misapplication of the law and are contrary to the constitutional rights of these parents to raise their children as they see best.”

Wiley Rein, which is representing the Meitivs on a pro bono basis, “intends to pursue all legal remedies to protect the Meitivs’ parental rights.”

Child Protective Services first began investigating the Meitivs in December after police stopped the children midway through a walk home from a different park after responding to a call from a concerned citizen. In that instance, police drove the children home but called Child Protective Services.

The Meitivs were notified in a February letter that they had been found responsible for “unsubstantiated neglect,” but they continued to let their children roam free around the neighborhood.

“Nothing that has happened so far has convinced me that children don’t need independence and freedom, except that they’ll be harassed by police and CPS,” Danielle Meitiv has said.

Follow WNEW on Twitter

(TM and Copyright 2015 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2015 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)