Dreams involving school shootings can be quite distressing and often evoke feelings of fear or anxiety. In your dream, the setting of a drive-thru while a school shooting occurs at night may suggest several themes:

1. Vulnerability: Schools are places of learning and safety, so a shooting there can symbolize feelings of vulnerability or anxiety in a space that should feel secure. The night setting may enhance this feeling of uncertainty or fear.
2. Waiting and Anticipation: Being at a drive-thru waiting for food may represent a sense of waiting for something in your life, whether it's a decision, opportunity, or change. The interruption of this mundane activity by a violent event could indicate that you feel your life is being disrupted by external circumstances or fears.
3. Fear of Chaos: The juxtaposition of a normal activity (getting food) with a chaotic and violent event might reflect your concerns about the unpredictability of life or societal issues. It could signify worries about safety in your environment or the impact of current events on your mental state.
4. Processing Trauma: If you've been exposed to news about violence, this dream might be a way for your subconscious to process those feelings. It could reflect a heightened awareness of danger in your surroundings.

To gain clarity, consider your feelings during the dream and any current issues in your life that may relate to feelings of fear or disruption. Journaling about these feelings or discussing them with someone you trust may help to further understand their significance. If these dreams persist and cause distress, consider speaking with a professional for additional support.