The train was reported to have run away from Paderno d'Adda without crew, and with a passenger detected after the derailment.

[1] The train was to operate a Paderno d'Adda-Milan service about 25 minutes after the start of the runaway from Paderno d'Adda, which took place about 15 minutes after its arrival from Milan;[2] it included a Class E.464 locomotive (in the rear position), six carriages and a control car.

After travelling for 7 kilometres (4.3 mi),[3] the train was diverted into a siding at Carnate-Usmate station.

[2] Three people were injured (the passenger, and the 2 crew members while trying to get on the runaway train in Paderno d'Adda); they all suffered minor injuries, and the passenger was taken to the hospital for checks.

The train event recorder was recovered from the E.464 and handed over to investigators.