WASHINGTON (Reuters) - U.S. auto safety regulators said Wednesday three people have been killed and two seriously injured by low-cost faulty replacement air bag inflators.

The National Highway Traffic Safety Administration urged used car buyers and owners to be aware of the use of substandard imported inflators that can cause death or serious injury in a crash. The agency said the inflators, which had been installed after prior crashes, malfunctioned in subsequent crashes, sending large metal fragments into drivers.