The National Highway Traffic Safety Administration (NHTSA) suspended passenger service for all U.S.-based EasyMile shuttles on Feb. 25, including a pilot with the City of Columbus, Ohio, that began in February.

This is in response to a “minor incident” after a passenger fell from their seat after the shuttle made an emergency stop, according to an EasyMile release. The vehicle, operating in the Linden neighborhood of Columbus, was traveling at a low speed of 7.1 mph.

“We operate at such low speeds precisely for this reason: our shuttles can make sudden stops when they detect a safety risk,” the release stated.

The company emphasized that it uses rigid safety protocols and is running test loops on the ground for analysis into the suddenness of the stop. Additionally, EasyMile stated that the company trains customer service ambassadors to remind passengers to hold on when the vehicle is in motion and place signage in the vehicles stating this.

“The [program] won’t return to service until NHTSA clears the vehicles and the City of Columbus is satisfied with the resolution of a technical and safety review. Smart Columbus is committed to passenger safety and to sharing our technology and safety learnings with other cities so they can benefit from this demonstration of new mobility technology,” said Alyssa Chenault, communications project manager for Smart Columbus, in an e-mailed statement.

Various public agencies nationwide are testing autonomous vehicles, including the National Renewable Energy Lab (NREL) in Golden, Colo., the City of Peoria, Ariz., the City of Fremont, Calif., and Texas Southern University in the Houston area. NREL and Texas Southern University are using EasyMile vehicles.