A volunteer firefighter has been placed under formal investigation in France on suspicion of deliberately starting one of the country's worst forest fires in decades, authorities have confirmed. The 18-year-old is among at least six people questioned in connection with the blaze that has consumed more than 2,000 hectares — roughly 5,000 acres — of the Fontainebleau forest, a historic woodland situated south of Paris that has been cherished by Parisians for centuries.

Prosecutor Diane Ngomsik told the AFP news agency that the young firefighter had initially confessed to "setting fire to twigs with a lighter and petrol" before retracting the statement. A second 18-year-old man has also been formally placed under investigation — a stage in French criminal procedure that can lead to charges and a subsequent trial — according to broadcaster BFMTV. Although the fire has now been contained, it has not been fully extinguished, and around 1,000 residents were evacuated as the blaze spread and partially closed France's main north-south motorway since it broke out last Sunday.

Visiting the affected area on Thursday, President Emmanuel Macron pledged zero tolerance for arsonists and noted that approximately 10 percent of the Fontainebleau forest had been destroyed. He described the scale of fires across France this year as unprecedented since the Second World War, with nearly 11,000 fires recorded since January. The Fontainebleau forest is home to the Palace and Park of Fontainebleau, a Unesco World Heritage site recognised since 1981, making the cultural as well as environmental loss particularly significant.

The fire comes amid a broader crisis driven by climate change. Europe is warming twice as fast as the global average, according to the Copernicus climate service, fuelling intense summer heatwaves, straining water supplies, and accelerating the spread of wildfires. This summer's record-breaking temperatures have triggered major fires across the continent, including blazes in Spain that have killed at least 13 people and a large-scale wildfire spreading across the Cairngorms National Park in north-east Scotland. The Fontainebleau case, if arson is confirmed, underscores the acute danger posed when human actions intersect with already volatile conditions — and why authorities are signalling an uncompromising response.