Kid Was Burned At Open House (my House For Sale)

My real estate agent held an open house for the home I am selling. My realtor had the gas fireplace on for ambiance. Apparently a family came to the open house and during their viewing, their 5 year old son swiped his hand over the gas fireplace and sustained burns to his hand.

They are now taking legal action and want to sue me for this. My question is: do they have grounds? Can this even go anywhere? Is my agent at fault for this or is this on me? Never been in this situation so any advice is appreciated.

Edited to add:

I see a lot of people referencing touching an open flame but just wanted to clarify that it's is a gas fireplace with the glass window. You cannot touch an open flame. It looks harmless but the glass gets extremely hot when the fireplace is left on for a bit. And this is what happened in this case. The fireplace almost looks fake or like a TV screen. Which is what is making me nervous in this situation. I appreciate all the feedback. I'm going to contact my insurance.