The four children went to several Alexandra homes at the weekend purporting to be raising funds for their school and other organisations.
Police say the children entered the houses without being invited in and in one case returned to the property and stolen several items.
Some of the missing property has been recovered and the children have been referred to a youth aid officer which is working with Child Youth and Family.
Sergeant Derek Ealson, of Alexandra, reminded resident to be cautious about visitors they don't know.
"Alexandra is a very safe community generally but we just wanted to let the community know about these events and remind people that the best place to talk with fundraisers or people who visit your home that you don't know is on the door step.
"The best thing is not to open the door to strangers. If someone claims to be a fundraiser then ask them for identification with a contact number so that you can verify their details.
"If you are not comfortable with the situation then contact a neighbour, friend or family member, or the Police."
