Police are investigating after reports that two children and a woman were bitten by a dog outside Carlton Junior and Infant School, Batley Carr.
The incident was reported to have taken place at around 8.44am on Monday and the victims received superficial leg injuries.
Head teacher Rizwana Mahmood said: “The incident occurred outside school grounds but we ask dog owners within the local community to remember that the safety of our children and staff is of paramount importance to us.
“We are supporting the police with their investigation and it would not be appropriate for us to comment any further.”
A West Yorkshire Police spokesman said: “Initial enquiries are underway to determine what took place and investigate the incident.
“Anyone who saw what happened or has information is asked to contact the Batley Neighbourhood Policing Team on 01924 295301.
“Messages can be left on a voicemail if the call is not answered.”