A worker for a Twin Cities contractor became trapped under a slow-moving concrete grinding machine Thursday morning while he worked on a highway north of Grand Forks and was killed, authorities said.

Dead at the construction zone on northbound Interstate 29 about a mile south of Manvel shortly before 8 a.m. was a 58-year-old man from Clear Lake, Minn., according to the North Dakota Highway Patrol. His identity was being withheld pending notification of family.

The man worked for Diamond Surface Inc. of Rogers, the patrol said.

The machine, weighing thousands of pounds, is used to mill concrete while being ridden by its operator.

The worker was next to the machine as it crept along when his legs got caught and pulled him under, said Patrol Sgt. Dolf Oldenburg. No one was seated on the grinder at the time, Oldenburg added.

The patrol will assist OSHA with investigating the death.

The company declined to comment about the incident.