HOPKINTON, Mass. — A Massachusetts State Police trooper suffered arm and hand injuries Wednesday when he was struck by a tractor-trailer that didn't stop, an agency spokesperson said in a statement.

The trooper was outside his cruiser on Interstate 495 north in Hopkinton checking on another truck that was stopped on the side of the highway when he was “sideswiped” at about 10:30 a.m., spokesperson David Procopio said.

The trooper, a lieutenant whose name was not made public, was taken to UMass Medical Center in Worcester.

The cruiser, a white unmarked vehicle, was also damaged.

Police are still trying to find the tractor-trailer, which had a blue cab and a white trailer, and may be a Freightliner from the model years 1998 to 2001.

The truck may have minor damage to its passenger side, and may have white paint transfer from the cruiser on it. Anyone with information about the truck is asked to contact police.