Police said on X the alleged perpetrator was detained “within several minutes” and the two children’s lives were not in jeopardy.

“A girl pupil attacked her schoolmates with a knife. Two children were injured and their parents have been informed,” police said.

“Both injured children, whose lives are not threatened, are undergoing treatment, just like another child who was in shock,” they added.

Regional governor Rudolf Spotak later told reporters that both children had been released into home care and their injuries were not serious.

The Blesk tabloid said the 13-year-old alleged perpetrator had stabbed a boy in the stomach and a girl in the back.

Regional police chief Petr Machacek said the girl’s motives were unknown.

Domazlice deputy mayor Viktor Krutina told reporters the attack occurred just before school began.

“Owing to the rapid reaction of a teacher and the headmaster, there were no further attacks elsewhere in the building,” he said.

Headmaster Ivan Rybar said the suspect attacked her schoolmates in a building for 12- to 15-year-olds.

He added that she was a Czech national and had never had discipline issues.

The school said on Facebook it had cancelled classes for older children “because of an extraordinary event”, while younger children stayed in class in the school’s other building.

The attack happened on the second day of the school year as teachers were planning to give pupils a lesson on safety, said Rybar.

Domazlice is near the Czech Republic’s western border with Germany, about 130km southwest of the capital, Prague.