I was just fired for getting injured?

I started a job 4 weeks ago as a iron worker/ concrete finisher. My 2nd week I got a hernia, I returned after 3 days off. After 3 days I injured my knee when a concrete form fell onto it, nothing serious just hurt pretty bad. They fired me and said im a liability? I got injured doing the work they told me to do, they asked me to lift the forms? I’ve never been fired wtf is this even legal