Can a Child Protective Service (CPS) worker question child/minor without parent/s consent or knowledge?

Can a CPS worker question a minor (10 & 15) without a parent/s knowledge or consent? CPS worker went to the school and questioned the 10 year old and learned that the 15 year old was not in school (home sick) and proceeded to the children's place of residence. Worker knocked and then attempted to open the locked door and then proceeded to walk around house looking in windows. Worker did not identify himself and 15 year old did not know the individual and was taught to not open door to strangers. Parents were at work and neither were notified of any impending action of the worker, thus the questioning of the 10 year old and attempted questioning of the 15 year old.