Image credit: Time Magazine
I would suggest not diving into a therapeutic project on the first day, week, or month after a disaster. Many may still be in shock or even still suffering through trauma, homelessness, family members who may still be suffering in a hospital, lost, or worse. Giving some time for healing is important, it also allows time to reflect and put things in perspective.
Too soon can open wounds that you are just not aware of.
Rather than "going it alone" and diving in, I'd STRONGLY urge you to consult with your guidance department about your ideas. They may know more personal information about your students, like who lost a parent, sibling, home, etc. If you have a school psychologist, USE THAT RESOURCE.
I have found that working symbolically is very helpful in these situations. It allows students to "code" their visual content so they can express their feelings in a very personal way, yet it still remains private. If you allow students to speak about their work, they should know they only need to share what they are comfortable sharing, even if it's just to talk about the colors they used.
The resource I recommend for this is the book, "The Emotional Color Wheel." It helps students code their feelings and experiences into colors and shapes. HERE are some specifics on how I use the lesson, and below is a free poster that I created to help students understand these color and shape connections. (You can download it below the image).
You might consider doing an anonymous secret vote on scrap paper, telling students your idea of a project, and letting them vote yes or no, but allowing comments so you know why they said no on that voting paper. Was it because they think it's boring, or was it because they are uncomfortable with the subject. This empowers students too, to be heard.
Consider partnering with another school that may be facing a similar situation, together you may be able to do a combined art show to help the community heal. You might be able to make it a fundraising event to help replenish supplies that may have been lost.
If the tragedy you face was one of violence, or great loss of life, I would suggest THIS article as a follow-up.