 This is Washington's Top News. WTOP News. Facts Matter. Now a quick look at what's trending. The most serious IT outage the world has ever seen is over. It was caused by an update to CrowdStrike's Falcon sensor software, which crashed. The blackout affected Microsoft apps in service for hours, with travel and medical industries amongst the worst hit. Hospital staff and patients shared clips about canceled surgeries and access to meds. In the operating room, pretty much nothing is working, and so no elective cases are happening.