How did the attack unfold?
The attacker stormed the centre in the town of Uthai Sawan, 500km (310 miles) north-east of Bangkok, at about 12:30 local time (05:30 GMT) on Thursday.
One of the teachers at the centre told local media they thought the man wanted something - after all, they knew him because his son attended the same centre, even though he had not been there for a month.
Carers tried to lock the doors, but the man proceeded to attack indiscriminately.
"The shooter came in around lunchtime and shot four or five officials at the childcare centre first," district official Jidapa Boonsom told Reuters news agency.
"At first, people thought it was fireworks," she said.
The attacker, she added, then forced his way into a locked room where children were sleeping, stabbing them. Only one is said to have survived.
A teacher who managed to escape described the knife "like one for cutting grass - it was curved".
From there, the man fled as police were alerted and launched a manhunt.
AFP news agency quotes an eyewitness who was riding a motorcycle to her shop when she saw him driving away erratically.
"The attacker rammed a motorbike and two people were injured. I sped off to get away from him," Paweena Purichan said, adding, "There was blood everywhere."
He fled the scene in a white four-door Toyota pick-up truck with Bangkok registration plates and went home, where he killed himself, his wife and their son, police said.
Who are the victims?
The number of fatalities is at least 38, including 22 children. Some of the children were as young as two.
A number of them were care centre staff, including some killed as they were having lunch outside the nursery and others who tried to lock the man out.
Other adults - and at least one of the children - were killed as the attacker fled from the scene.
At least 12 people have been wounded.