The aim of this study was to determine the frequency of anxiety, depression, and irritability symptoms in children during the COVID-19 outbreak and to investigate the associated factors of these symptoms. This study was conducted with 1071 children aged 6 to 17. Results showed that 49.9% of the participants had anxiety symptoms, 29.5% had depression symptoms, and 51.4% had irritability symptoms. Low age was a potential risk factor for anxiety symptoms. Female sex was a potential risk factor for anxiety and depression symptoms. A COVID-19 death in the family or environment was a potential risk factor for depression and irritability symptoms. Exposure to COVID-19 information on television and on the internet was a potential risk factor for anxiety, depression, and irritability symptoms. In conclusion, this study revealed that the COVID-19 outbreak may have serious effects on the mental health of children, and the study highlighted potential risk factors.