WASHINGTON — Self-driving cars could present safety challenges on the road and national security threats if terrorists load them with explosives.

That was the warning to federal regulators during a public hearing on how to best move forward with automated vehicles.

The public hearing, at the U.S  Department of Transportation headquarters, was the first of two hearings planned nationally.

Saying the vehicles could be turned into a “sort of a drone on wheels,” James Niles, president of New York tech company Orbit City Lab, said terrorists could take advantage of early autonomous vehicle services, such as on-demand taxis, and use them as ways to deliver explosive or radiological devices.

“For the most part,” he said, “the concern that autonomous vehicles could be used as a weapon has gone unnoticed by the general public, and probably a majority of government officials,” referencing a 2014 FBI report.

He said regulators should require autonomous vehicles be equipped with sensors capable of detecting hazardous materials. Then the vehicle could be disabled if something is detected.

“People have a lot of great ideas. Some are being enacted, but there’s also a need for a lot more brainstorming about what the threats could be,” said National Highway Traffic Safety Administration leader Mark Rosekind. “New technology represents new vulnerabilities and risks as well. This is like ‘eyes wide open.’”

He said cyber threats to vehicles are still a main concern.

Leaders say it’s possible the nation is near the point of seeing widespread automated technology being deployed. They are looking to develop effective guidelines for the vehicles.