Full Self driving did not show signs of slowing down at Everett traffic slow down from about 60 miles to a standstill. I realized the speed not slowing down (about 5 car distance from stopped distance) I tried to apply the brakes that were completely nonresponsive, instead the car sped up. I avoided backend collision with the first car be maneuvering to the shoulder, however the next car was parked halfway into the shoulder that didn't leave enough room to not hit it. The car hit two other cars before coming to a full stop. While checking for any injuries for myself and passenger, after a delay and hitting 3 cars the airbags uselessly deployed. Total failure of brakes, auto emergency braking and airbag deployment. I have requested Tesla to look into the logs but havent gotten any feedback.