Police are looking to trace a man who tried to persuade two young boys to get into his car.
He approached the 11-year-olds separately in the East End Park area on Wednesday morning.
A nearby primary school, Richmond Hill Academy, sent a text alert to parents to warn them of the incident.
West Yorkshire Police said:
"At about 8.40am a man in a silver-grey car with blacked-out windows approached an 11-year-old boy near to the junction of Pontefract Lane and Cross Green Lane.
"He also approached another 11-year-old boy in Pontefract Lane a short time later.
"He offered each of them a lift and drove off when they refused.
“We are carrying out inquiries in the area, including checks on CCTV, and officers from the local neighbourhood policing team have increased their patrols of the area to reassure the community.”