Toddler was pushed down a flight of stairs at daycare

My son's daycare is built on a slope and they have to go down the stairs to get to the playground. They usually go multiple times a day and have taught him how to go down the stairs safely. Today, another kid shoved him and he fell down an entire flight of stairs. Thankfully, his doctor does not think he has a concussion or a serious head injury. His face is very banged up though and I'm incredibly upset. They are very lucky he is not more seriously hurt. I want to ask more questions and make sure they are taking steps to ensure this doesn't happen again. What would you do in my case? Part of me wants to pull him out but I think I may be overreacting.