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.

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.

The news out of London that Heathrow Airport was closed Friday because of a fire and huge power outage had ripple effects all the way to Boston, even as the airport began to resume some flights.All seven flights that were due to arrive at Logan Airport Friday afternoon and evening have been cancelled,