The Transportation Security Administration is warning American truck owners and operators to be on the lookout for terrorists who would use large commercial vehicles in ramming-type attacks.

The warning comes in an unclassified report that was sent to law enforcement agencies across the country on Tuesday entitled “Vehicle ramming attacks: Threat landscape, indicators and counter measures.” The report comes after U.S. law enforcement agencies reported an increased threat of truck ramming attacks.

From the report: “Commercial vehicles — distinguished by their large size, weight and carrying capacity — present an especially attractive mechanism for vehicle ramming attacks because of the ease with which they can penetrate security barriers and the large-scale damage they can inflict on people and infrastructure.

The TSA says that events like parades and sporting events are particularly vulnerable to truck ramming attacks and that U.S. law enforcement agencies have uncovered several planned attacks for these types of events.

The report tells truck drivers and truck owners to immediately report a stolen truck and to be on the look out for odd modifications on trucks. This could include attempts to reinforce the front of the truck with metal plates.

During the last three years, 173 people have been killed and 700 more injured by truck ramming attacks worldwide.

Subscribe for top trucking news updates