A 37-year-old caretaker has died after being stabbed by a former pupil at a school in Poland, police have said.

The 15-year-old entered the primary school in Leszczydół-Nowiny, north of Warsaw, at around 09:00 (07:00 GMT) and attacked the caretaker, 37, before being overpowered by a teacher and the school's headteacher who were also injured.

Polish police said they had also detained a 17-year-old boy in another town after he had indicated an intention to do "something spectacular" at his school.

Both incidents come a day after a 19-year-old was arrested on suspicion of a stabbing attack at another Polish school in which seven people were injured.

The 15-year-old who attacked the caretaker was carrying three knives, Poland's interior ministry spokesperson Karolina Galecka said.

The boy used to study at the primary school, but his motives for the attack are unclear, Galecka added.

Polish media report that the caretaker had tried to stop the 15-year-old from entering the school.

The teacher and the headteacher's lives are not in danger, the ministry's spokesperson said.

Before news of Thursday's stabbing in Leszczydół-Nowiny, Mazowsze Police announced it had prevented a separate school stabbing in the region.

Interior Minister Marcin Kierwiński said the 17-year-old detained in the town of Sierpc, north-west of Warsaw, "had stated on school grounds that he planned to do something... dangerous - that he intended to harm someone".

Teachers had alerted the police, who found that the teenager was in possession of two knives.

"The young person had been searching for information on how to orchestrate a 'bloody' event of this kind," Kierwiński said.