Authorities warn terrorists may try truck-ramming attacks in U.S.

CHICAGO (WLS) -- A transportation security administration report is warning of truck-ramming attacks by terrorists. This comes nearly seven years after the I-Team first reported plans by al Qaeda to use trucks as "killing machines," possibly in downtown Chicago.

In 2010 the I-Team uncovered a new al Qaeda publication called "Inspire" that instructed jihadists to use pickup trucks as "the ultimate mowing machines." Now, seven years later, federal authorities are warning that terrorists may try truck-ramming attacks in the U.S.

This comes as American counter-terrorism investigators are warning local police on how to diagnose someone going from sympathizer to attacker.

Read the full National Counterterrorism Center Report here.

In the past three years, there have been 17 ramming attacks worldwide; leaving at least 173 people dead, with suspected terrorists behind the wheel mostly using trucks as weapons. More than 700 people have been injured in the attacks.

In most cases, authorities say the inspiration and the instructions have come from terrorist manuals including that al Qaeda magazine first reported by the I-Team in October 2010.

Would-be jihadists urged to put plows on pick-ups and then run them into downtown crowds. Chicago's North Michigan Avenue area and the John Hancock Tower were pictured in an accompanying article, encouraging Islamists to wage their own personal holy war on America.

Thursday night a new TSA report obtained by the I-Team warned truck owners and truck rental agencies in the U.S. about the increasing frequency of "ramming attacks" by terrorists -- and that no community is immune from 'lone wolf' terrorists.

The TSA report urges vehicle owners to report thefts or suspicious activities such as attempts to reinforce the front of a vehicle with metal plates.

The National Counterterrorism Center Report obtained by the I-Team, entitled "Homegrown Violent Extremist Mobilization Indicators," has been provided to Indiana law enforcement. It offers behavior traits that may indicate a terrorist sympathizer is being radicalized and moving toward violence.

Among the telltale signs are the obvious, such as "preparing and disseminating a last will or martyrdom video," but of particular concern for local police fearing a truck-ramming attack would be if a suspect was seen "surveilling potential targets."

TSA investigators have also identified indicators that terrorists may be planning a vehicle ramming attack and countermeasures that can be taken. Thursday, a TSA spokesman told the I-Team that the truck ramming guidance was shared last week with trucking and bus industry officials, warning that these low-tech methods of attack are becoming more commonplace around the globe.