A freight train derailed near Station Square in Pittsburgh. (Photo: Isaac McDaniel)

A freight train derailed Sunday in Pittsburgh, sending rail cars down a hill and onto light-rail tracks below, disrupting transit service, authorities said.

Norfolk Southern, the freight operator, said there were no reports of injuries and no hazardous materials were involved. The derailment occurred near the Station Square complex in Pittsburgh’s South Shore neighborhood.

Seven rail cars went off the tracks when the train derailed at 1:13 p.m., according to Norfolk Southern. The railroad said it was a 57-car “double-stack” shipping train, meaning some containers were stacked atop one another.

A locomotive engineer and conductor were aboard the freight train, which was traveling from northern New Jersey to Chicago, the company said. The train, carrying goods such as food products, beverages, housewares and other retail items, was more than a mile long and weighed nearly 5,000 tons, Norfolk Southern said.

The Port Authority of Allegheny County, the city’s public transit agency, said light-rail service was disrupted by the derailment after the Norfolk Southern railcars spilled over from the tracks above.

Norfolk Southern said the cause of the derailment was unknown late Sunday, but the railroad had ruled out a rock slide. The company expects the cleanup to take up to 72 hours.

“As we work 24/7 with local officials to resume operations and restore normal traffic patterns, Norfolk Southern apologizes to residents for any inconveniences caused by the derailment,” the railroad said.

The scene of the train derailment in Pittsburgh on Sunday. (Photo: Isaac McDaniel)