State Police detectives assigned to the Suffolk County District Attorney’s office are investigating the death of a 56-year-old pedestrian struck and killed by a Chelsea Police cruiser responding to a call for assistance late last night.

Preliminary investigation by State Police indicates that the Chelsea man, who will not be named until his family has been notified, entered the roadway on foot and was struck by the cruiser at about 11:15 p.m. The cruiser was responding with active lights and sirens to assist Everett Police engaged in pursuit of a suspect.

The officer operating the cruiser remained at the scene and notified Chelsea Police dispatchers. Responding emergency medical technicians transported the pedestrian to Whidden Memorial Hospital, where he was pronounced dead of his injuries. The officer was treated at and released from Massachusetts General Hospital.

The State Police Collision Analysis and Reconstruction Section responded to process the scene and take custody of the cruiser. Crash reconstruction experts will attempt to estimate the cruiser’s speed at the time of the collision. Members of the State Police Crime Scene Services Section also responded to assist in evidence collection and documentation. Chelsea Police have pledged their assistance as well.

State Police assigned to the Suffolk DA’s office have jurisdiction over all unattended and unnatural deaths in Chelsea, Revere, and Winthrop.