Scene of a fatal tractor accident on a bridge over the Machias River near Holmes Falls in Northfield on Thursday, Sept. 24, 2009. (Bangor Daily News photo by Sharon Kiley Mack) Buy Photo

NORTHFIELD, Maine — Jonathan Brock, 21, of Addison was killed Thursday morning when the tractor he was operating plummeted off a wooden bridge over the Machias River in a remote area of Washington County near Holmes Falls.

Brock was coming down an incline and was hauling an empty utility trailer when he apparently lost control, Washington County Sheriff’s Deputy Brandon Parker said.

The 80-foot-long wooden bridge has small wooden bumpers along its outside edge that were visibly chewed up by the tractor as it left the bridge deck.

As it tumbled off the bridge, the tractor flipped upside down. Rescue workers reported that Brock was pinned upside down under the tractor in about six feet of water. The tractor, a large industrial machine, did not have an enclosed cab.

Parker said it had not been determined yet whether Brock died of drowning or from the impact.

The tractor and utility trailer were owned by Cherryfield Foods and were demolished.

The accident happened just feet from Holmes Falls, a scenic camping and fishing area, which is 13 miles from Route 1 in Columbia Falls and approximately 10 miles from Route 9. Rescue personnel had to travel on rough gravel roads through 7 miles of woods and blueberry barrens to reach the scene.

The accident was reported at about 10 a.m. by a co-worker who was following Brock in a pickup truck. That worker attempted to rescue Brock, but was unable to free him and summoned help.

Members of the Washington County Sheriff’s Department, Marine Patrol, Inland Fisheries and Wildlife, the Columbia Fire Department, the Cherryfield Foods Hazardous Materials Team and Pleasant River Ambulance responded to the report.

Several law enforcement officers were able to get to the scene quickly because they were at the site of a marijuana eradication and investigation in nearby Township 37.