US President Donald Trump called the blaze engulfing Notre Dame cathedral in Paris "horrible" on Monday and suggested the deployment of flying water tankers.
"So horrible to watch the massive fire at Notre Dame Cathedral in Paris. Perhaps flying water tankers could be used to put it out. Must act quickly!" Trump tweeted.
Fire spread rapidly through a major portion of the magnificent Gothic cathedral at the heart of Paris.
The Paris mayor, Anne Hidalgo, said the fire service was "trying to control the flames."