A picture taken on April 16, 2019 shows Notre-Dame-de-Paris in the aftermath of a fire that devastated the cathedral. Paris was struck in its very heart as flames devoured the roof of Notre-Dame, the medieval cathedral made famous by Victor Hugo, its two massive towers flanked with gargoyles instantly recognisable even by people who have never visited the city. (Photo by Bertrand GUAY / AFP)
PARIS: French investigators interviewed construction workers involved in renovation work at the Notre-Dame cathedral on Tuesday as they sought to identify the source of a devastating blaze at the monument that has sent shockwaves through France and the world.