The National Highway Traffic Safety Administration (NHTSA) agreed to review a petition signed by 127 Tesla owners who accuse their car of suddenly and unexpectedly accelerating. The agency stressed it hasn’t detected a problem yet.

The owners who signed the petition cited alarming examples of unintended acceleration experienced in the Model S, the Model X, and the Model 3. They experienced the defect in 123 cars, meaning a handful filed more than one complaint, and they blamed it for 110 crashes and 52 injuries. They’re asking NHTSA to recall 500,000 cars manufactured between the 2012 and 2019 model years, which represents a vast majority of the cars Tesla has made.

The reports of sudden unintended acceleration are varied, and they don’t follow a set pattern. Consumer Reports wrote a motorist from Henderson, Nevada, who claims he suffered a broken rib when his 2017 Model S accelerated while he was pulling into a parking spot. The incident caused $18,000 in property damage. Another motorist claims to have spent half an hour driving between 65 and 70 mph on the highway without being able to slow down in a 2015 Model S. The car stopped after it crashed into the vehicle it was following, according to a complaint, and its airbags deployed.

The car unexpectedly surging forward as it’s crawling into a parking spot or a garage bay is a scenario that comes up often, Reuters reported. None of the complaints shed light on the cause of the problem or provide details about what happens when the driver presses the brake pedal to override the electric powertrain.

Assuming there is indeed a problem, it might be software- or hardware-related, or it could be caused by something much simpler. For example, in 2009, Toyota recalled 3.8 million cars because the driver-side floor mat could slide forward and pin down the accelerator pedal, causing the vehicle to speed out of control.

NHTSA hasn’t revealed how long it will take to decide whether to launch a formal investigation into the matter. Consumer Reports warned Tesla owners “it would pay to keep close tabs on how your vehicle is operating, though it’s too soon to make any conclusions about the safety of these cars.” Tesla hasn’t commented on the petition.