WASHINGTON, D.C. — A recent memo from the Transportation Security Administration (TSA) informs transportation providers about the use of vehicle ramming as a terrorist tactic.

In the unclassified security awareness message, dated April 27, TSA provides details on vehicle ramming incidents and offers related security tips for surface transportation stakeholders. The message is signed by Sonya Proctor, director of the surface division for TSA’s Office of Security Policy and Industry Engagement.

TSA points to several recent instances of rented vehicles being used in attacks in Europe and Canada. That includes the April 23 incident in Toronto in which a man in a rented van allegedly drove onto a crowded sidewalk, killing 10 people and injuring at least 15 others.

“This incident highlights the potential for vehicle ramming as a terrorist tactic,” Proctor writes in the security awareness message.

TSA also issued a fact sheet with data on vehicle ramming attacks in the U.S. The agency identified four terrorist-related vehicle attacks on pedestrians in four states — North Carolina, Ohio, Virginia, and New York — that have occurred since 2001. Those incidents resulted in a total of 10 fatalities and 41 injuries.

In the incident in New York, on Oct. 31 last year, police said that a man driving a rented pickup truck entered a bike path in Manhattan’s West Side and struck multiple pedestrians and cyclists. The truck then collided with a school bus, injuring two children and two adults who were on board. In all, the attack killed eight people and injured about a dozen.

The TSA security awareness message advises surface transportation operators to encourage their employees to secure their vehicles to prevent theft or unauthorized use. Also, “Employees should review their company’s security policies and procedures. Persons whose behavior does not fit their circumstances or surroundings should be brought to the attention of law enforcement.”

The agency recommends that contact information for company supervisors, local law enforcement, and the local FBI field office be made readily available to employees to assist them in reporting suspicious activity.

The message does not point to a specific threat.

“At this time, the TSA Office of Intelligence and Analysis (TSA OIA) is not aware of any current or credible plots to attack transportation within the United States,” Proctor writes. “However, TSA OIA remains concerned with terrorist organizations’ efforts to conduct attacks against transportation. Threat actors in the Homeland may be influenced by successful overseas attacks to target transportation in the United States.”

The TSA security awareness message on vehicle ramming can be downloaded here.

Meanwhile, on May 9, the Department of Homeland Security (which includes TSA) reissued its National Terrorism Advisory System (NTAS) Bulletin, which is used to describe developments or general trends related to terrorism and, like the TSA vehicle ramming message, is not an alert of a specific threat. The current edition of the NTAS bulletin extends to Sept. 14.

“Terrorist groups are urging recruits to adopt easy-to-use tools to target public places and events,” the Department of Homeland Security says in the bulletin. “Specific attack tactics have included the use of vehicle ramming, small arms, straight-edged blades or knives, homemade explosives, and poisons or toxins.”