Police found the burned-out pickup truck used by a gunman after killing at least 36 people in a rampage through a nursery this afternoon.

Footage shows the horrific aftermath of the carnage, with bodies found at several buildings and in the street around the pre-school in Nong Bua Lamphu province in the far north of the country.

Police Lieutenant Panya Khamrab, 34, who was suspended from the force several weeks ago for drugs offences, allegedly killed children and adults including his wife and own son before turning the gun on himself.

His white Vigo pickup truck was found abandoned at a nearby home having been set alight.

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.

Police said 19 boys, three girls and two adults were found day inside the childcare centre. One boy and an adult were found dead at a nearby government office.

While at the shooter's home, one boy and four adults were reportedly killed and another adult was shot dead in a nearby building.

A further three people - all adults - were pronounced dead at hospital.

At least 12 other people were injured in the rampage and are being treated at hospital.