The children were on a walk in the city's Łazarz neighborhood when a 71-year-old man approached the group and stabbed one of them in the chest around 10 a.m. local time.
A passerby managed to disarm the attacker, and an off-duty policewoman apprehended the assailant.
In a tweet, Polish police said: "In Poznań, there was a shocking knife attack on a group of preschoolers who were on a walk with their caregivers. The perpetrator was arrested by a policewoman passing by the scene of the incident in her off-duty time."
Following the attack, the boy received immediate attention at the scene but died after being rushed to a hospital.
The motives behind the incident remain under investigation.
(jh/gs)
Source: PAP, IAR