DETROIT (AP) — U.S. safety regulators are investigating thousands of Volkswagen SUVs because the headlamps and other outside lights can fail with little warning.

The probe, announced Friday by the National Highway Traffic Safety Administration, affects an estimated 61,000 VW Tiguans from the 2009 through 2011 model years.

The safety agency said in documents posted on its website that 26 drivers have complained about headlights, tail lights and turn signals going dark. Many said they found an overheated and melted fuse under the hood. The agency said the fuse controls several exterior light circuits. The complaints say the problem gets worse over time.

NHTSA said the problem hasn't caused any fires, crashes or injuries. Investigators will determine if it's bad enough to prompt a recall.

Volkswagen said it's committed to building safe vehicles and will comply with the NHTSA investigation.

In one complaint from August, a driver told NHTSA that the headlights and brake lights stopped working. "The danger is that this has happened three times, and once at night, to where my car was like a Christmas tree blinking on and off," the driver wrote. "I almost got rear-ended when brake lights don't work."

The driver said the Tiguan was taken to a dealership, where mechanics couldn't find the source of the problem. Many other drivers reported melted fuse boxes after the lights failed.