Child Mind Institute explains:

When students go through something traumatic, their grief and fear often show up in the classroom. Teachers can make a big difference by actively supporting students, especially if the traumatic event happened at school.

First, acknowledge the loss openly. Students need to know that they can talk about what happened if they want to. The most important thing is just to listen, even if you're not sure what to say. A safe, comfortable space to talk to someone they trust about how they're feeling is incredibly valuable. Invite questions and answer them as best you can, but don't require students to participate before they're ready. Students may also be worried about their own safety, especially young ones

Once you've given space to process what happened, returning to the school routine is very comforting for students. It also shows them that tragedy isn't the end of the world and that it's possible to move forward in a healthy way.

Finally, remember that coming to terms with loss takes time. Help students find ways to cope with their ongoing feelings and remember the people they lost.