The U.S. government has launched an investigation into nearly 1.9 million RAV4 sport utility vehicles manufactured by Toyota Motor for potential engine fire risks, Business Insider and Kyodo News reported Tuesday.

The National Highway Traffic Safety Administration started investigating after receiving 11 fire complaints involving Toyota RAV4 built between 2013 and 2018.

Based on a summary of the investigation, most of the 11 fires happened while the vehicles were underway and identified the 12-volt battery as the origin in most cases. However, four fires were reported while the engine was off.

The administration said improper installation of the battery or front-end collision repair was a factor. The administration said the RAV4 had more fire complaints associated with batteries compared with other vehicles.

Many of the reports were from vehicles with fewer than 50,000 miles on the clock, the agency said.

"Drivers experienced stalling before the thermal event in half of the instances where the vehicle was in motion," USA Today quoted administration investigators as saying.

At least two drivers said they were "lucky to be able to walk" from their burning vehicles and hoped to warn other drivers who may be at risk, Insider said.

Around 430,000 RAV4 units were sold in 2020, making the SUV the Japan automaker's bestselling vehicle in the U.S. The second top-selling SUV is the Honda CR-V, with 333,502 units sold.

Toyota is cooperating.