Hyundai and Kia are rolling out software updates to stem a raft of auto thefts related to a TikTok challenge that authorities believe has led to at least 14 reported crashes and eight fatalities.

The updates are free for millions of vehicles that are missing a key anti-theft device, an issue that was exploited on social media and led to rampant theft of the cars.

The software being released updates the theft alarm software logic to extend the length of the alarm sound from 30 seconds to one minute and requires the key to be in the ignition switch to turn the vehicle on.

About 3.8 million Hyundais and 4.5 million Kias are eligible for the software update, the National Highway Traffic Safety Administration said Tuesday.

Hyundai said updates begin Tuesday for nearly 4 million vehicles beginning with a million model year 2017-2020 Elantra, 2015-2019 Sonata and 2020-2021 Venue vehicles. The software upgrade is scheduled to be available for the remaining eligible vehicles by June.

“We have prioritized the upgrade’s availability for owners and lessees of our highest selling vehicles and those most targeted by thieves in order for dealers to service them first,” said Randy Parker, CEO of Hyundai Motor America.

Kia said it had already begun to update the software for some vehicles.

In September the Highway Loss Data Institute, a unit of the Insurance Institute for Highway Safety, found that Hyundais and Kias without immobilizers had a vehicle theft claim rate of 2.18 per 1,000 insured vehicle years. The rest of the industry combined had a rate of 1.21. An insured vehicle year is equal to one vehicle insured for one year.

The institute compared vehicles from the 2015 through 2019 model years. It studied vehicle theft claims from 2021.

Hyundai says all models produced after Nov. 1, 2021 have immobilizers as standard equipment.

TikTok Videos Show How to Easily Hotwire Cars

A TikTok social media challenge put a spotlight on the vehicles’ lack of an immobilizer and resulted in at least 14 reported crashes and eight fatalities, according to the NHTSA. The challenge shows TikTok viewers how to hot-wire Kia and Hyundai cars with a USB cord and a screwdriver.

In October a police commissioner said that a car crash in Buffalo, New York that left four teenagers dead may have been linked to the TikTok challenge. In the incident, a total of six teenagers were in a speeding Kia that crashed, Buffalo police said. The car had been reported stolen.

Hyundai and Kia will start software updates later this month, with subsequent phases over the next several months. Hyundai will also provide window stickers to vehicle owners that alert would-be thieves that the vehicle has anti-theft protection.

Vehicle owners can contact Hyundai at 800-633-5151 and Kia at 800-333-4542 for information on the software update.