Two people have been killed after a high-speed train derailed on Thursday near the northern Italian city of Lodi, emergency services say.

Photo: AFP

Both of the dead are drivers. A cleaner on the train and one other person suffered significant but not life-threatening injuries.

The train was travelling from Milan to the southern city of Salerno.

All services on the Milan-Bologna high-speed route have been suspended and diverted via conventional lines.

While there have been occasional crashes on Italy's regional trains, this is the first such incident on its high-speed Frecciarossa - or Red Arrow - network, the country's transport pride.

The trains, which run at 300 km/h are generally efficient, punctual and safe.

The engine left the tracks around 40km from Milan at around 5.30am local time (5.30pm Thursday NZT), the railway company said.

It apparently hit a freight wagon on a parallel track before running into a building and was separated from the rest of the train. Both it and the first carriage turned on their sides.

"I thought I was dead," a survivor told local newspaper Liberta. "I closed my eyes and prayed.

"The train was going very fast... suddenly, I felt a violent blow. A really loud roar."

The survivor added that he and a friend were stuck on the train for 15 minutes before escaping through a hole.

The causes of the accident are being investigated.

Ansa news agency said maintenance work was being carried out on the track where the accident happened.

There were 28 passengers on the train, Ansa said, a number of whom received minor injuries.

Lodi Prefect Marcello Cardona said the accident "could have been carnage" but there were only 33 people on the train at the time, and no more fatalities were expected.

Dozens of trains were cancelled and others re-routed, train operator Trenitalia said.

-BBC