Police from Bangkok's Hua Mak station are hunting for a man aged about 25 who viciously kicked and knocked down a small boy for no apparent reason as he walked past the child and his grandmother in the street.
A video taken by a passing car shows the man, seemingly in his mid-20s, walking along the footpath towards the approaching grandmother and child. As he passes them he suddenly lashes out with his left leg, kicking the boy in the head.
The boy falls to the ground and the assailant continues his walk as if nothing had happened.
The attack occurred near Ramkhamhaeng Soi 83/5 on Ramkhamhaeng Road in Bangkok about 1pm on Sunday, the social media centre of the Royal Thai Police Office said on Monday.
The grandmother, identified only as Lee, took the boy to Phramongkutklao Hospital for treatment. He had swelling to the head. A doctor prescribed painkillers and recommended his symptoms be monitored at home.
Investigators were examining surveillance camera footage in the area to track down the man, police said.