The National Highway Traffic Safety Administration has reportedly taken an interest in reports that models of Ford’s Ford Explorer, from the model years 2011 to 2013, are leaking exhaust fumes containing potentially fatal amounts of carbon monoxide into the passenger cabin.

One customer, a firefighter featured in the video above, tested the airflow coming into the cabin as having carbon monoxide levels at 132 parts per million. Levels over 100 are considered to be hazardous to one’s health, the news report explained. Angela Knutson, the owner of a 2013 Ford Explorer, said that a defect in hundreds of thousands of Explorers could cause “lethal quantities of carbon monoxide” to enter passenger cabins while the vehicle was being driven and thus putting occupants at risk, Reuters reported, quoting the lawsuit dated June 9.

Though Ford actively does not comment on open litigations, the company is seemingly aware that something’s amiss. In December, it issued a technical service bulletin to dealers acknowledging that some Explorers from model years 2011 to 2013 “may exhibit an exhaust odor in the vehicle with the auxiliary climate control system on,” Reuters said. Knutson then filed the suit, claiming that Ford neglected to warn its customers or even acknowledge the possibility that passengers may be exposed to carbon monoxide gas. In the Explorer in particular, it’s especially concerning to families with small kids who are shuttled around frequently.

The NHTSA, in a statement on the situation, said that it was “reviewing all available data and will take appropriate action as warranted.” Knutson, her husband (who is also the firefighter mentioned previously), and their kids have been driving the Explorer for two years, though have stopped using it since the carbon monoxide test returned such extreme numbers. Knutson noted that their kids had thrown up on long car trips, despite seeming perfectly fine healthy otherwise.

Ford made an attempt to fix the issue, but the Knutson’s law firm argues that the fix — replacing air extractors in the rear compartment — hasn’t worked. The firm is pushing for a recall of the affected vehicles. Within the timeline of 2011 to 2013, that would equal hundreds of thousands of vehicles up for recall, the video explains.