U.S. safety regulators have opened a probe into an estimated 110,000 heavy-duty Chrysler Group Ram pickup trucks with manual transmissions after reports that the vehicle had started when the clutch was not engaged.

The National Highway Traffic Safety Administration has opened a preliminary evaluation into Dodge Ram 2500 and 3500 pickups from model years 2004 through 2006 after receiving three complaints, including one involving a death, according to documents filed online. The problem was described as a possible failure of the clutch interlock switch.

“One complaint involved an incident that occurred when a child was able to enter the vehicle and start the ignition without depressing the clutch. The vehicle then moved forward striking another child resulting in a fatality,” NHTSA said.

The incident took place in August 2013 and a complaint was filed with the safety agency in February.

A second complaint said the engine was cranked without the clutch pedal depressed while an individual was standing directly in front of the vehicle performing work under the hood.

“The clutch interlock failed to prevent the engine from cranking, which resulted in vehicle movement into the pedestrian performing work under the hood. The individual was knocked to the ground, but did not report any injuries,” NHTSA said.

The National Highway Traffic Safety Administration said Friday it is opening an investigation into 110,000 older Dodge Ram pickups that may have faulty interlocks to prevent a child from starting the vehicle.

The safety agency said it had three reports that 2004-06 Dodge Ram 2500 and 3500 manual transmission trucks could be started even if the driver’s foot was not on the clutch.

Vehicles are required to have a clutch interlock to ensure that the vehicle can only be started if the clutch is depressed.

A preliminary investigation is the first step in a process that could lead to a recall if regulators determine that a manufacturer needs to address a safety issue.

Chrysler said it is “cooperating fully with this investigation.” The automaker added that “customer safety is paramount.”