Arsonists could be behind a major power cut at theCannes Film Festival, according to French police. The power cut caused chaos just hours before the festival's star-studded closing ceremony, with local media suggesting it could have been caused by "malicious acts". The French national gendarmerie confirmed that officials were "looking into the likelihood of a fire being started deliberately", reported Reuters. It added that no arrests had been made so far. Mobile networks, 4G, traffic systems and train lines were all affected, making travel and communication difficult. The headquarters of the festival switched to a backup power supply that organisers hoped would allow the closing ceremony to take place. An official statement from the festival said: "A power outage is currently affecting the city of Cannes and surrounding areas. At this stage, the cause of the outage has not yet been identified. Restoration efforts are under way. "The Palais des Festivals has switched to an independent power supply, allowing all scheduled events and screenings, including the closing ceremony, to proceed as planned and under normal conditions." The first signs of power trouble were seen ahead of a press conference with The Crown star John O'Connor, when a loud bang was heard in the festival building, before it was plunged into temporary darkness. Guests were later seen paying for drinks and ice cream in cash, while expensive local restaurants lost the use of card machines. France Info, a radio network, broadcast unconfirmed reports that two "malicious acts" took place along train lines in the Var region, to the west of Cannes, before the blackout. Broaden your horizons with award-winning British journalism. Try The Telegraph free for 1 month with unlimited access to our award-winning website, exclusive app, money-saving offers and more.