ROME -- One person was dead and dozens injured in a tram derailment on Friday in northern Italy's Milan, local media reported.

The accident occurred in late afternoon when the Line 9 tram derailed and crashed into a building, leaving one person dead and 40 others injured, said Italian news portal Corriere della Sera, citing witnesses as saying the vehicle was traveling at high speed before the crash.

Italy's Rai News said that the tram, which derailed in the Porta Venezia area of Milan, plowed into a building and killed a passerby. Another 39 people got injured, and one among them was under serious condition.

The cause of the derailment is still unknown. An investigation is underway by the authorities.