HACKENSACK, N.J. (CBSNewYork) — Homeland Security is issuing a warning to trucking businesses about a low-tech, but frighteningly effective, terror tactic.

As CBS2’s Tony Aiello reported, the recently unclassified warning from the feds says, in part: “There are several indicators that may suggest terrorists are planning a commercial vehicle ramming attack, which can occur with little to no warning.”

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Homeland Security is asking businesses to increase vigilance in order to guard against such potentially deadly attacks.

Last July, a terrorist drove a rented truck into a Bastille Day crowd in Nice, France.

Five months later, an ISIS supporter killed a truck driver, stole his rig and smashed into a Christmas market in Berlin.

At Bergen Brookside Towing in Hackensack, employees already keep a watchful eye on their fleet and facilities. Soon, their drivers will be briefed on the Homeland Security warning.

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“It’s scary to think that someone’s going to be stealing a commercial vehicle with the intent to injure or kill someone,” said Steve Salemme of Bergen Brookside Towing.

Between 2014 and April of this year, terrorists committed 17 vehicle ramming attacks — 173 people died, almost 700 were injured.

The TSA is warning drivers to be aware of their personal safety and to secure their rigs.

“We make sure all of our drivers don’t leave their trucks unattended with the keys in them,” Salemme said.

The NYPD says potential truck terror has long been on its radar. The city takes steps to block attacks at big events and authorizes officers to fire on a moving vehicle that represents a danger to the public.

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The NYPD says it regularly checks with truck rental companies to monitor possible suspicious activity.