I have a 94 s10 4x4 and right now driving down the street it started making a strange noise and the brake pedal goes all the way to the floor and vibrates. If I turn the ignition on it still makes the noise. What could be wrong?

 

Sounds like it could be an ABS problem. Is the ABS light on? How about the Check Engine light? Are there any stored codes?

 

Sounds like you ran out of brake fluid. Buy some at the local gas station/parts store and fill her up. Then have someone hit the brake pedal while you are watching underneath and around the car. You'll find the leak pretty easily, then just replace whatever is leaking (most likely a line has ruptured)

DONT sit under the car while they press the pedal though, you don't want to get that stuff in your eyes. If the leak is small, it will spray like a bottle of febreeze

 

Watch the brake fluid as it will eat the paint off everything it touches!