A 17-year-old Dundalk resident was seriously injured in Glen Burnie early Wednesday when a co-worker backed a dump truck into a large oak tree, pinning the teen-ager against it.

Patrick Ross Allen, of the 2900 block of Liberty Parkway, was in serious condition at Maryland Shock Trauma Center yesterday evening, a nurse said. Allen was taken there after the accident at 7:45 a.m. Wednesday near Central Avenue.

Police said Allen was standing on the left rear step of the truck when driver Wayne Lawrence Schemm, 62, of the 3500 block of Horton Ave. in Baltimore backed the vehicle into the tree.

Allen's legs, hands and chest were crushed, but he remained conscious at the scene, police said. Allen also suffered numerous internal injuries, police said.

An investigator from the Maryland Occupational Safety and Health office has been assigned to the case, police said. Charges have not been filed, police said, but an investigation is under way.

Allen and Schemm work for Gunther Refuse Service of Hanover.