A statistical resource from the US Department of Health and Human Services:
https://www.acf.hhs.gov/cb/report/child-maltreatment-2020
It took a couple of hops from Bryan on Scouting to find it, so I thought I'd drop it at a top level here.
There are overall national stats as well as executive summaries from individual state agencies.
Regarding maltreatment
Regarding fatalities