In acute crisis situations, social media can play a crucial role in rapidly disseminating vital information. But there is also a risk that false or outdated facts are spread, causing unwarranted fear or panic. In a new study, Moa Eriksson Krutrök, Associate Professor of Media and Communication Studies, and Simon Lindgren, Professor of Sociology, both at Umeå University, investigated how information about a suspected terrorist attack on the London Underground in 2017 was spread via Twitter. The terror alert, which created uncertainty among the public, soon turned out to be false. But by then it was already too late, alarming reports were spreading like a digital wildfire.