Start with safety
Make sure no one is being hurt and get help if someone is in danger. Long explanations can wait. You may need a break as well, provided your child is safely supervised.
Talk about what happened later
Describe the situation as specifically as you can and ask how your child experienced it. You can acknowledge the feeling and hold a boundary at the same time: anger is allowed; hurting people is not.
Choose one thing to try
Instead of a new list of rules, agree on one possible response: a pause signal or a phrase for asking for help. Everyday experience will show whether it is useful.
Take frequent or dangerous outbursts seriously
Intense, persistent or escalating outbursts need professional assessment, particularly where there are injuries or significant difficulties in daily life. In immediate danger in Germany, call 112.