A lorry carrying margarine and flour catches fire inside the Mont Blanc Tunnel, creating an inferno that kills 38 people.

On 24 March 1999, a transport truck caught fire while driving through the Mont Blanc Tunnel between France and Italy. When it stopped halfway through the tunnel, it violently combusted. Other vehicles traveling through the tunnel quickly became trapped and they also caught fire as firefighters were unable to reach the transport truck. 39 people were killed. In the aftermath, major changes were made to the tunnel to improve its safety.

The Mont Blanc Tunnel is a highway tunnel between France and Italy, under Mont Blanc in the Alps. It links Chamonix, Haute-Savoie, France with Courmayeur, Aosta Valley, Italy, via the French Route Nationale 205 and the Italian Traforo T1, in particular the motorways serving Geneva and Turin. The passageway is one of the major trans-Alpine transport routes, particularly for Italy, which relies on this tunnel for transporting as much as one-third of its freight to northern Europe. It reduces the route from France to Turin by 50 kilometres and to Milan by 100 km (60 mi). Northeast of Mont Blanc's summit, the tunnel is about 15 km (10 mi) southwest of the tripoint with Switzerland, near Mont Dolent.

March 24 is the 83rd day of the year in the Gregorian calendar; 282 days remain until the end of the year.