OSPEDALETTO LODIGIANO, Italy (AP) — A high-speed passenger train derailed in northern Italy before dawn Thursday, killing two railway workers and injuring 28 other people as its engine broke off and careened into a work vehicle on a adjacent track. Authorities are looking into human error linked to track maintenance work as a possible cause.

The state-railway Freccia Rossa train went off the rails on the heavily used Milan-Bologna line while traveling at nearly 300 kph (180 mph), Civil Protection chief Angelo Borrelli told state radio.

Maintenance work had been carried out on a nearby track switching area less than two hours before the derailment, Prosecutor Domenico Chiaro told reporters at a news conference

The train that derailed was the first train to pass through the area after the work was done and “the switch was placed in a position it shouldn't have been,” he said.

“We're looking into the hypothesis of human error that could be linked to the maintenance work,” as a possible cause for the accident, Chiaro said, stressing that no conclusions had been reached yet.

Sabotage or a terror attack have been ruled out, the prosecutor said and investigators have recovered the train's black box recording.

“The (engine of the) train rammed a series of obstacles'' before finally stopping, Chiaro said, including a nearby building used for storing railway equipment and tools. The engine car ended its fatal trajectory flipped around 180 degrees.

State railways said the two fatalities were train engineers. Prefect Marcello Cardona said another railroad worker was seriously injured. Among the 27 passengers hurt in the derailing, one was seriously injured, authorities said.

“The engine car kept going, hundreds of meters, at high speed,” Cardona told reporters at the crash site near the town of Ospedaletto Lodigiano.

Chiaro said the crash occurred about 5:50 a.m. (0450 GMT), several minutes after a scheduled stop as the train traveled from Milan south to Bologna.

Police said the train had about 30 passengers. Only one passenger was in the first car, a business-class car, that ended up on its side. The train passenger cars further back remained upright.

One passenger, an unidentified man interviewed by state TV, likened the moment of the crash to being on a roller-coaster for 20 seconds.

Authorities said it was possible that the engine car automatically decoupled from the cars behind it as part of a safety mechanism during derailments.

The passenger train run is part of a popular high-speed rail service known as Freccia Rossa, or the Red Arrow service, which links Italy's north and south.

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Colleen Barry in Milan and Frances D'Emilio in Rome contributed to this report.