birth control, pregnancy tests, std screenings and more. tonight four cities stopped mass shootings or bombing attacks. two suspects had white supremacist leanings and two were obsessed with mass shootings. nbc's pete williams now with the details. >> reporter: in a florida supermarket, authorities arrest a man 12 hours after getting a tip he was making threats. the county sheriff says 25-year-old tristan wix of daytona beach sent disturbing text messages to his exgirlfriend including, quote, i want to open fire on a large crowd of people. investigators say he was fascinated with mass shootings in connecticut, brandon wag shaw was arrested after a tip said he bought high powering magazines out of state he too was interested in mass violence he signed a statement saying he did not have intention of committing mass shooting in ohio, a search turned up four weapons after social media posts