The election brought about a litany of “firsts.” The first woman nominated for president by a major political party. The first president-elect with no military or formal political experience. Among all of the unfamiliar facets to the 2016 campaign season, the deluge of fake news from fake news websites—concocted primarily to stoke theories popular in conspiracy circles—has proved very influential.

And on Sunday, their influence nearly proved deadly.

The fictional PizzaGate “news story” spread like wildfire among the Facebook fever swamps, rife with standard conspiracy fare: hidden tunnels, government sanctioned child sex rings. Real tinfoil hat stuff. But with this fake news story came real consequences, when an armed man entered Cosmic Ping Pong in Washington, D.C. to “investigate” the claims. The gunman fired at least one shot inside the pizza joint before surrendering to authorities.

The influx of fake news on social media was already a massive story prior to Sunday’s events, but now the game has changed. It’s no longer just trolls spreading false information; it has real world consequences. When you have vigilantes armed with assault rifles entering buildings to investigate conspiracy claims, something has to be done.

It’s a high wire act for online outlets, however. The First Amendment guarantees the right to free speech, so Facebook and Twitter are toeing a delicate line. You don’t want to infringe on the freedoms of your user-base, but when the deliberate spread of false information leads to outcomes like we saw on Sunday, the safety of that same user-base is in jeopardy.

What a strange world.

The thing about conspiracy theories is that they’re never really solved. Once one is debunked, another swiftly takes its place. It’s already occurring with PizzaGate, as many are now claiming the events were a “false flag” designed to discredit the fake allegations. Paranoia is a hell of a drug; its remedy only appearing to be more paranoia.

Let’s hope this is the first and last instance of fake news conspiratorial fantasy impacting real life.