NEW GLOUCESTER — A Lewiston driver was killed and her four passengers critically injured when their car went off the Maine Turnpike on Monday night and slammed into a tree, Maine State Police Trooper Duane Doughty said.

The dead woman was identified as 52-year-old Rebecca Abukook of Walnut Street, who died instantly at the scene.

Her passengers were Maria Dengdot, 38, sisters Nybul Lual, 32, and Ayok Lual, 28, and Achel Madut, 50, the investigator said. Dengdot and Ayok Lual were taken to Maine Medical Center in Portland; Madut and Nybul Lual were taken to Central Maine Medical Center in Lewiston. All four suffered broken bones and internal injuries and were in critical condition early Tuesday morning, the trooper said.

Abukook was driving south in her 1995 Toyota Camry about 6:20 p.m. when the car drifted off the highway and into a tree, he said. The reason is unknown at this time, he added, and the investigation is continuing.

The scene was near mile 67 about 2,000 feet north of the turnpike toll barrier, he said.