The U.S. government appears poised to order a recall of millions of air bag inflators due to a manufacturing flaw that could send metal shrapnel rocketing through a car’s interior.

The National Highway Traffic Safety Administration held a public hearing Thursday to field commentary and testimony on inflators made by ARC Automotive Inc. of Knoxville, Tennessee, which supplies the devices to air bag makers and several major auto companies. At least 25 million vehicles containing ARC-made air bags could be affected.

At the heart of the issue is a metal inflator canister inside the airbag device. The government contends that a crucial flaw could cause this canister to “rupture” upon impact. Instead of releasing pressurized gas to inflate the air bag, the canister essentially explodes, sending metal shrapnel into the vehicle at head height.