ROME -- A commuter train derailed in the northern Lombardy region on Thursday, leaving at least three people dead and five others seriously injured.

The train derailed at a switch track between Treviglio and Pioltello at the outskirts of Milan at around 7 am local time, according to Trenord regional railway company.

At least 350 commuters were on board of the train, which left Cremona in eastern Lombardy region at 5:32 am, and was due to reach Milan's Garibaldi station in about two hours.

A provisional toll at midday mounted to three victims and five people in critical conditions, Ansa news agency reported citing Milan prefect's office.

Another eight people needed to be hospitalized, and some eighty passengers traumatized or with light injured were assisted by the Red Cross at a sport facility in the town of Pioltello.

Firefighters worked for hours on the scene to try to free passengers trapped in the debris, and all rescue operations were completed at around 10 am, the Fire Corp stated on Twitter.

At least two carriages from the middle of the train were involved in the derailment, and pictures from the scene showed them partially upturned off the rails. According to passengers who shared testimonies with local media and on twitter, the train started to tremble a few minutes before the incident occurred.

A structural damage of about 20cm on a track -- some 2 km before the actual place of the incident -- was determined by technicians of Italy's state railway operator Rete Ferroviaria Italia (RFI), Ansa news agency said citing sources from the company.

RFI technicians would have ruled out any malfunctioning in the switch tracks in the Pioltello station.

Speaking to reporters at the scene, Milan police commissioner Marcello Cardona confirmed that "a material failure was pinpointed" and an investigation for culpable disaster was launched.

However, the official warned that "all the checks needed to draw a clear picture of the situation have yet to be completed".

Regional connections were halted in the morning, while fast trains between Milan and Venice in northeast Italy were not disrupted, Milan prefect's office also said in a statement.

This was the latest episode in a series of deadly incidents involving Italy's railway network. In 2016, two trains collided while traveling on a single track in southeast Ppulia region, leaving 23 people dead.

In 2009, some 32 people were killed when a cargo train carrying liquefied gas derailed in the Tuscan city of Viareggio at night, causing an explosion that engulfed the station and some blocks of apartments nearby.