Power Steering Light On problems of the 2001 Toyota Sequoia

Traveling on the freeway at a speed of 55 miles the vcs trac control light came on and the brakes were applied with out me hitting the breaks, I lost control of the steering for a slight second, the truck swerved to the left, it almost cause me to hit a car on the left of me on the freeway. Once I turned the car off, the vcs trac lights turned off, then it happened again on the street at a lower speed of 45 mile the vcs trac light started to flash and the brakes were applied and the truck swerved to the left, the lights stayed on again until I turned off the truck.