DETROIT (AP) — The U.S. government is stepping up its quest to force ARC Automotive to recall 67 million potentially dangerous air bag inflators by ordering the company to answer questions under oath and threatening fines if it doesn’t respond.

NHTSA argues that the recall is justified because two people have been killed in the United States and Canada and at least seven others have been injured by ARC’s inflators. The explosions, which first occurred in 2009, have continued as recently as this year.

The special order from the National Highway Traffic Safety Administration asks multiple questions about whether ARC expects any of its inflators to blow apart in the future, and whether it has notified customers about the risk.

The agency wants ARC Automotive Inc., based in Knoxville, Tennessee, to recall the inflators, which could explode with such force as to blow apart a metal canister and expel shrapnel. But ARC is refusing, setting up a possible court fight.

ARC maintains that no safety defect exists, that NHTSA’s demand is based on a hypothesis rather than technical conclusions and that the agency has no authority to order a parts manufacturer to carry out recalls.

NHTSA has tentatively concluded that the inflators are defective. The next steps are a final conclusion, public hearing and potential lawsuit asking a judge to order a recall.

Since ARC inflators can be in both driver and passenger front air bags, people who travel in at least 33 million U.S. vehicles could be at risk.