A former police officer armed with a gun and a knife stormed a nursery in northeast Thailand on Thursday, shooting dead at least 34 people including children before killing himself and his family, police said.

The attacker, armed with a shotgun, a pistol and a knife, opened fire on the childcare centre in Nong Bua Lam Phu province at about 12:30pm, local time, before fleeing the scene in a vehicle, the force said.

"The death toll from the shooting incident... is at least 30 people," Anucha Burapachaisri, a spokesman for the Thai prime minister's office, said.

Police colonel Jakkapat Vijitraithaya, from the province where the attack happened, identified the gunman as Panya Khamrab, a police lieutenant colonel he said was dismissed from the force last year for drug use.

Jakkapat said there were 23 children among the dead, aged two to three years old.

The mass killing comes less than a month after a serving army officer shot dead two colleagues at a military training base in the capital Bangkok.

While Thailand has high rates of gun ownership, mass shootings are extremely rare.

But in the past year, there have been at least two other cases of shooting murders by serving soldiers, according to the Bangkok Post.

And in 2020, in one of the kingdom's deadliest incidents in recent years, a soldier gunned down 29 people in a 17-hour rampage and wounded scores more before he was shot dead by commandos.

That mass shooting was linked to a debt dispute between gunman Sergeant-Major Jakrapanth Thomma and a senior officer, and the military top brass were at pains to portray the killer as a rogue soldier. - Agencies