A Massachusetts State Police trooper was killed while on duty late Thursday night when the driver of an oil tanker struck her cruiser as she attempted to help a stopped motorist on Interstate 93 in Stoneham, authorities said Friday.

The crash that killed Trooper Tamar Bucci, 34, of Woburn, happened around 11:45 p.m. on the highway’s northbound side, according to State Police Col. Christopher Mason.

The impact of the crash pushed Bucci, in her marked Ford Interceptor cruiser, off the road, he said.

Two good Samaritans pulled Bucci from her damaged SUV, and a Stoneham police officer who came upon the scene performed CPR until Bucci was brought to Massachusetts General Hospital, where she was pronounced dead, Mason told reporters at a press conference.

“Late last night, on a stretch of road that she protected every night during the midnight shift, Trooper Bucci gave her life in the act of trying to help another person in distress,” Mason said shortly after sunrise Friday morning. “There is no greater act of sacrifice than to give one’s life for another.”

The department is “devastated by her loss,” Mason said.

“We are eternally grateful for the attempts of everyone involved to assist Trooper Bucci and to save her life,” he said.