Government safety regulators are investigating 1.4 million Toyota vehicles – including the country's most popular car, the Camry – after more than 100 reports of fires.
On Monday, the National Highway Traffic Safety Administration added 600,000 Camrys, Camry Hybrids, RAV4s and Yaris vehicles from model years 2007 through 2009 as well as 2008 Highlander Hybrids to its existing probe.
Investigators are looking into electrical fires that can spark in the driver's door armrest when the power window switch overheats.
Since launching the examination in February,Toyota Motor Corp. and regulators have received 161 complaints of fires or crashes. Nine people have reportedly been hurt but no deaths were noted.
So far, the government agency hasn't initiated a recall into the matter.