A gunman opened fire at a children's day-care centre in Thailand killing at least 31 people including adults and children.

Local media reported that the shooter was a former policeman who fled the scene shortly after the rampage in a white Toyota pickup truck.

Dozens of bodies covered in blood were scattered across the floor and on the grounds outside the Child Care Center Uthai Sawan Subdistrict Administrative Organization in Nong Bua Lam Phu province in the far north of the country.

Officers are yet to arrest the suspect, named by local media as Police Lieutenant Panya Khamrab, 34, from the Na Wang district police station in the same region as the incident.

A gunman opened fire at a nursery killing at least 20 people including children and adults in Thailand this afternoon.

Dozens of bodies covered in blood were scattered across the floor and in the grounds outside the Child Care Center Uthai Sawan Subdistrict Administrative Organization in Nong Bua Lam Phu province in the far north of the country.

Local media reported that the shooter was a former policeman who fled the scene shortly after the rampage in a white Toyota pickup truck.

Officers are yet to arrest the suspect, named by local media as Police Lieutenant Panya Khamrab, 34, from the Na Wang district police station in the same region as the incident.