In 2015, brothers Robert and Michael Bever murdered 5 members of their immediate family. They planned to go on a killing rampage and they stood in the way.

https://linktr.ee/KillerStories

sources:
Oxygen series 'Killer Siblings' Season 1, Episode 4
https://en.wikipedia.org/wiki/Broken_Arrow_killings
https://tulsaworld.com/news/local/history/six-years-ago-five-members-of-bever-family-murdered-in-broken-arrow/collection_83f33ca0-cfad-11eb-8334-27b061d835c8.html#2
https://www.oxygen.com/killer-siblings/crime-news/robert-michael-bevers-stab-family-broken-arrow-crystal
https://tulsaworld.com/news/local/crime-and-courts/broken-arrow-family-killer-robert-bever-gets-additional-life-sentences-for-attempted-attack-on-prison/article_bc799210-290c-11eb-87dd-03c07f6bd5ae.html
https://www.khits.com/story/5e35c21d2f69d76f620114cf/robert-bever-tries-to-attack-prison-staff-with-sharpened-instrument-report-states
https://abcnews.go.com/US/wireStory/oklahoma-court-rejects-appeal-fatal-stabbing-people-71453654
https://ktul.com/news/local/doc-moves-michael-bever-to-holding-facility-in-cleveland-county