There are still a lot of unanswered questions about what led to a tragic mass shooting in a Texas church on Sunday. These types of breaking news situations shed light on the importance of fact-checking, and combating fake news. PolitiFact's Staff Writer Jon Greenberg says trolls immediately go into clickbait mode in these situations. Greenberg says on Monday, he noticed trolls made up false information about the shooter's identity and background. These trolls want the advertising revenue, and don't care what it takes to get it says Greenberg. PolitiFact is currently partnering with Facebook to tackle the social media giant's fake news problem. Greenberg says they can't stop fake news from surfacing, but through their efforts, they flag highly-questionable stories to Facebook so they don't make it to the top of users' newsfeeds. But ultimately, the best defense against fake news is savvy consumers, says Greenberg.