The spire of the gothic cathedral of the French city of Rouen in Normandy caught fire on Thursday, television images showed.
The cathedral, one of France's finest, was painted several times by impressionist artist Claude Monet in the 19th century.
Television images on BFM channel showed a dark plume of smoke rising from the spire and people in the streets below looking up in horror. The scene was reminiscent of the devastating fire at Notre-Dame cathedral in Paris in 2019.
The local prefect, a state official, said the cathedral had been evacuated and emergency services were on the scene. A security cordon was in place around the building.