Britain’s Heathrow Airport has closed for the full day Friday after an electrical substation fire knocked out its power, disrupting flights for hundreds of thousands of passengers at one of Europe’s biggest travel hubs.

London’s Heathrow Airport, one of the world’s busiest, will be shut all day Friday due to a “significant power outage” as a result of a large fire nearby, airport officials said. Follow for live updat

A giant fire near one of the world’s busiest airports knocked out power, and the cause was under investigation. Hundreds of flights were canceled or rerouted, and analysts said disruptions could last days.