Background. Suicide is a major public health concern globally and is a burden to families and society. The National Mental Health Strategy and Program for Suicide Prevention 2020–2030 in Finland, suggested 36 measures for suicide prevention. One of them is increasing knowledge of first encounter professionals, such as police officers, in suicide prevention, as they have an important role in identifying people at risk of suicide. Methods. The project called “Challenging interaction situations. Encounters with a person who is at risk of suicide or suffers from mental health disorder” was carried out during 8/2021-12/2022. This project aimed to add police officers’ competence and awareness in challenging interactional situations with an individual who is at risk of suicide or suffers mental disorder. The first phase was to collect information about police officers’ current knowledge and needs about suicide prevention and mental health disorders as well as their attitudes and opinions concerning suicide and suicidal persons. The first version of online training was created and piloted. After evaluation of the pilot the online training was modified. After the development of the final online training of suicide training for police officers, a survey was conducted among those who had completed the online training. The survey included the same questions about knowledge and attitudes as the pre-survey. Results. According to before and after survey of the police officers’ knowledge had increased in many areas. Furthermore, their attitudes and understanding towards suicide and suicidal persons was more positive. Discussion. It seems that even a relatively short suicide prevention training increases police officers’ readiness to encounter persons with mental health disorders and in risk of suicide. As first encounter professionals they have a crucial role in preventing suicides and diminishing false beliefs.