A Metro worker was hit by a train early Tuesday afternoon in a maintenance yard near the Shady Grove station, according to Metro and rescue officials. The worker, who is a mechanic, suffered serious injuries, but he was reported to be conscious and alert, officials said.

The mishap occurred just before 1 p.m., officials said. Rescue workers were called to the yard — where trains are washed, maintained and repaired — and found the victim trapped by the train, said Capt. Oscar Garcia, a spokesman for the Montgomery County Fire and Rescue Service. The yard is in the 15900 block of Somerville Drive.

Garcia said rescue workers called physicians to the scene, which they do when more advanced medical procedures may be needed. The victim has since been extricated and taken to a hospital by helicopter.

The worker, who has been with Metro for more than 25 years, was struck by a service train, which does not carry passengers said Dan Stessel, Metro’s chief spokesman. The incident is not affecting rail service.

Metro is conducting a safety stand-down at Shady Grove Yard, where employees are offered counseling and safety practices are reviewed.

Metro has launched an investigation into the incident and has notified the National Transportation Safety Board and the Tri-State Oversight Committee, Stessel said.