WASHINGTON, D.C. (BNO NEWS) — The U.S. National Highway Traffic Safety Administration (NHTSA), part of the Department of Transportation, on Thursday said it will open a formal investigation into allegations of momentary loss of braking capability in the Toyota Prius Hybrid MY 2010.

The Administration said its Office of Defects Investigation received at least 124 reports from consumers, complaining that they lost braking capability while traveling over an uneven road surface, pothole or bump. Four of the reports alleged that crashes occurred as a result of the failure.

“Safety is our top priority,” said U.S. Secretary of Transportation Ray LaHood. “That is why in recent weeks NHTSA has also issued a consumer advisory on the recall of several models of Toyota vehicles and the Pontiac Vibe involving pedal entrapment and sticky accelerator pedals. We will continue to monitor these issues closely.”

Toyota president Akio Toyoda last week assured LaHood that Toyota takes U.S. safety concerns seriously and puts safety at the top of the company’s priorities.

Toyota’s public image, and its sales, have been hit by two recent recalls involving unintended acceleration. The automaker recalled 2.3 million vehicles on January 21 because of problems with sticking gas pedals and later halted the sale of the eight models involved in the recall. It also recalled 4.2 million vehicles in a separate recall in November for a problem in which the cars’ gas pedals could get stuck in some floor mats. Toyota’s U.S. sales plunged 16 percent in January, while other automakers reported positive results.

Earlier on Thursday, Toyota managing officer Hiro Yuki Yokoyama said a software glitch is the cause of the Prius braking problems. Yokoyama asked for more time to address the issue.

The NHTSA currently has 40 open defect investigations, three of which involve Toyota.