When Violence Among Children Crosses the Line – Can We Recognize the Signs in Time?

The incident that occurred on 11 September 2026 at Zagreb’s Electrical Engineering School, known as “Končar”, has once again raised the difficult issue of violence among children and adolescents.

According to information published in the media, a first-year secondary school student seriously injured another student with a knife, while a female member of staff who tried to intervene was also injured. The incident caused fear among students and parents, but also raised many questions: how does a child come to engage in such serious violent behavior, and can we recognize some of the signs earlier?

A single violent incident does not necessarily mean conduct disorder

After events like these, it is understandable to look for an explanation. However, it is extremely important not to make diagnoses based on media reports.

Aggressive behavior can occur in different circumstances and be associated with numerous factors. One isolated incident, even a very serious one, is not in itself enough to establish a diagnosis of conduct disorder.

In child and adolescent psychiatry, conduct disorder involves a repetitive and persistent pattern of aggressive, dissocial or markedly defiant behavior that violates the rights of other people or age-appropriate social norms. Possible manifestations may include frequent intimidation of others, initiating physical conflicts, serious fights, using objects or weapons that can injure another person, cruelty, theft, or serious and repeated rule-breaking.

Violence rarely has only one cause

In children and adolescents, serious aggressive behavior usually cannot be explained by a single trait, a single event or a single “culprit”.

The development of behavioral problems is understood as the result of interactions between numerous factors — individual, developmental, family-related, psychological and social. These may include impulsivity and difficulties with emotional regulation, traumatic experiences, family circumstances, academic failure, problems in peer relationships, exposure to violence, and co-occurring mental health difficulties.

It is particularly important to know that ADHD, depressive or anxiety symptoms, and substance misuse may also occur alongside behavioral problems.

That is why the question after a serious incident should not only be “How should this child be punished?”, but also “What had been happening in this child’s life before things reached this point?”

Which changes should adults not ignore?

Not every argument, act of disobedience or instance of adolescent rebellion is a sign of a serious disorder. However, behavior that recurs, intensifies or begins to seriously impair a child’s functioning deserves attention.

It is particularly important to respond to repeated threats and intimidation of others, increasingly intense physical conflicts, marked impulsivity and uncontrolled outbursts of anger, deliberately injuring others, serious rule-breaking, alcohol or drug misuse, a sudden deterioration in functioning at school, or pronounced changes in peer relationships.

It is equally important to notice what is less visible: withdrawal, depressive symptoms, anxiety, feelings of rejection, prolonged anger, difficulties regulating emotions, or statements in which a child talks about harming themselves or others.

Assessment must therefore not focus solely on the incident. It is necessary to speak with the child, their parents and, when needed, the school, and to consider how the child functions in different settings.

What can we do before serious violence occurs?

Prevention does not begin at the school gates, nor only when a weapon appears.

It begins much earlier — by recognizing changes in behavior, making professional help available, maintaining communication between parents and the school, and taking threats, repeated violence and sudden changes in a child’s functioning seriously.

In more serious cases, intervention often needs to involve several parts of the support system: the child, parents, school, psychologist, child and adolescent psychiatrist and, when necessary, other services. It is precisely because of the complexity of these problems that the professional literature emphasizes a multimodal and multidisciplinary approach.

At the same time, children who have witnessed serious violence also need our attention. After a traumatic event, they may develop a fear of returning to school, sleep difficulties, an increased need to be close to their parents, irritability, withdrawal, or a tendency to keep returning to the event. They should not be forced to talk about what happened, but they need to know that adults are available, that they are listening, and that restoring a sense of safety is a priority.

Let’s talk to children before a problem becomes a crisis

Events such as the one at the Zagreb school understandably cause fear and strong emotions. But after the initial shock, it is important to avoid stigmatization, oversimplification and rushing to a diagnosis.

Not every aggressive child has conduct disorder. Not every withdrawn child is dangerous. And there is no single sign that allows us to predict serious violence.

What we can do is notice changes earlier, take warning signs seriously and ensure that a child receives professional help before the problem escalates.

Violence among children is not only a problem for the child who committed the violence, nor only for their family. It is an issue of safety and mental health for the entire community.

Talk to your children. Ask them how they are — and listen to the answer.