Police in Yunnan province have set up checkpoints on roads in their search for a 3-year-old boy who was allegedly kidnapped on Sunday morning.

Police in Yongsheng county, Lijiang, said they received a call around 10:30 am on Sunday saying that a boy was seen being led into a white van by a woman while playing near his home in Yongbei township.

Officers immediately started a search, inspecting vehicles and people in the area. They also asked members of the public to come forward if they can provide valuable information.

The boy's father, surnamed Feng, said his 6-year-old daughter witnessed the abduction. She chased the van and demanded the woman free her brother, he told local media.

The young girl－who remembered the woman had a bob hairstyle and was wearing a purple top and jeans－was left traumatized, Feng said.

He and his wife had left the children with their grandparents on Sunday morning before going to work, Feng said.

The grandmother took the children with her to herd cattle, but left them unattended when she had to round up some cattle that strayed. When she returned, she found only the boy's sister, crying on her own. A passerby helped her call police, Feng added.