A SEPTA trolley was struck by a freight train in Delaware County on Thursday morning, sending six people, including the trolley operator, to the hospital with injuries.

A Route 11 trolley was traveling eastbound toward Center City around 8:30 a.m. when its front passenger side was hit by a CSX freight train at Sixth and Main Streets in Darby, where the two transit systems cross paths, said SEPTA spokesperson Andrew Busch.

Five passengers and the operator sustained injuries, mostly to the neck and back, Busch said. They were transported to a nearby hospital, and all were treated and released by 3 p.m., he said.

The cause of the crash is under investigation, Busch said.

The National Transportation Safety Board, a federal agency that investigates transit accidents, has also launched an investigation, he said.