my sister doesn't allow us to help her

Yesterday she had an argument with my parents. She was shouting at them and cussing them. while they were really calm and tried to calm her down as well. She locked herself in her room afterwards and started hitting the wall most of the night. Today they went to her room to check on her after she woke up and she was still angry and crying at the same time. When they tried to reason with her by asking how they can be of any help she started screaming from the top of her lungs telling them to leave. What's the best way to approach this situation?