This is an excellent article from The Child Mind Institute: https://childmind.org/guide/helping-children-cope-traumatic-event/
You can find information on Tips for Helping Children After the Event, Tips for Helping Kids Recover in a Healthy Way, How to Help Children Ages 0-2, How to Help Children Ages 2-5, How to Help Children Ages 6-11, and How to Help Children Ages 12-18. You can also find What Teachers Can Do to Help Students.
Dr. T