Car Owners Urged to Take 'Immediate Action' Over Airbags

The government is urging nearly five million drivers to take "immediate action" to protect themselves against "defective" airbags - airbags that a safety expert says can explode in the vehicle and harm passengers.

"This message comes with urgency," reads a post on the website for the National Highway Traffic Safety Administration, as it urges owners of "certain Toyota, Honda, Mazda, BMW, Nissan and General Motors vehicles to act immediately on recall notices to replace defective Takata airbags." The message is especially urgent for drivers in warm climates like Florida, Hawaii, Puerto Rico, Guam, Saipan, American Samoa and the U.S. Virgin Islands, NHTSA said.

The NHTSA lists more than 4.7 million vehicles with model years from 2000 to 2006 - in addition to the 2011 Honda Element -- that have been subject to related recalls over the past two years and urge owners to take them to their dealers.

Auto safety expert Sean Kane told ABC News the problem with the Takata airbags is its internal inflator.

"[It's] the canister which sits in the center of the airbag, it's like a metal can," Kane said. "When that's ignited, it's overpressurizing the canister and the canister is exploding, much like an IED [improvised explosive device], and sending shrapnel into the occupants of the vehicle."

Kane said that the explosions have caused "severe lacerations" and a reported four deaths.

Earlier this month Florida woman Hien Tran was killed in a mysterious auto accident in which she was found with stab-like wounds to her neck, according to The Orlando Sentinel. Last week, detectives determined the injuries were "consistent with... exploding airbags bags."

A week after Tran's death, Tran's family reportedly received a recall notice from Honda urging them to replace the 2001 Accord's airbag.

In a post on its website today, Toyota issued its own "supplemental" safety recall for more than a quarter million vehicles with airbags supplied by Takata, saying the "influence of high absolute humidity" in the malfunctions is under investigation. Toyota noted that it has not received any reports of injuries or deaths linked to the issue.

NHTSA opened an investigation into the airbags in June and in response, Takata said it has been "consistently cooperating with NHSTA, and we will continue to do so during the defect investigation... but we also stand by the quality of our products."

"Takata is committed to ensuring the safety and functionality of its air bag inflators and we strive to avoid any malfunction," the company said in June. ABC News was unable to reach Takata representatives at their U.S. headquarters for an updated comment.

Kane told ABC News he's "troubled" by how long it has taken to address the problem and urged car owners to see if their vehicle is affected by going to NHTSA's Safercar.gov website.