After receiving three reports of wheels falling off the Hummer H2, federal regulators are now investigating the vehicles, according to the National Highway Traffic Safety Administration (NHTSA).

The investigation includes Hummer H2s from the 2003 and 2004 model years, and General Motors Corp. said there are approximately 59,670 of them on the road.

Four Hummer H2 drivers reported a fracture in the steering knuckle, which allows the wheels to turn. All four of the drivers said they lost control of the vehicle, and in one instance, the driver's H2 veered into oncoming traffic and ended up in a ditch on the opposite side of the road. In three of the reported cases, a wheel fell off the vehicle.