NHTSA of the United States launched an investigation into GM's self-driving business Cruise due to improper braking and passengers trapped in the car.

CTOnews.com The National Highway Traffic Safety Administration (NHTSA) announced earlier this week that it is investigating Cruise, a self-driving business unit owned by General Motors. NHTSA said it had received three reports of traffic accidents that it believed were caused by "improper braking" while providing autonomous taxi services.

CTOnews.com understands that NHTSA also said it received multiple reports of passengers trapped inside vehicles. Passengers trapped inside the vehicle cannot leave, which NHTSA believes can lead to unsafe conditions for passengers and may cause other drivers to make dangerous moves to avoid hitting Cruise vehicles.

Cruise spokesman Drew Pusateri responded to the federal investigation in an email, CNBC reported, adding that we need to balance innovation with healthy regulatory scrutiny. While crashes and minor injuries caused by Cruise cars have federal regulators concerned, there have been no reports of fatalities caused by Cruise self-driving taxis.

Cruise self-driving taxis operate only in San Francisco, a complex and densely populated city, so it's not surprising that cars get into accidents.