Police arrested a mentally-ill man after he entered a Chaiyaphum primary school carrying a big knife and slightly injured a teacher on Wednesday morning.
The incident happened about 8am at Ban Namphu Hinlard School in Khon San district.
The arrested man's house is opposite the school. He entered the school grounds, driving fast on a motorcycle, as about 100 children and their teachers were gathering for morning assembly, police said.
The man held a big knife in his hand and slightly injured a teacher, as staff and children ran into the main building.
The intruder then left the school on his motorcycle and hid in his house. Police spent more than an hour talking to him and calming him down, and finally arrested him.
Police and teachers said he was mentally ill. The man was taken to Khon San Hospital. His name was not released.