Sounds like a brake pad came apart. That happens more commonly on rear pads when the car has rear disc brakes. The lining rusts off the backing plate and falls out. As you pump the brake pedal a few times, the piston self-adjusts out of the caliper, then you get the normal pedal back again. You'll hear that metal backing plate grinding against the rotor.
Be aware that once the repairs are completed, the master cylinder may have been damaged and need to be replaced. Crud and corrosion build up in the bores where the pistons don't normally travel. When the pedal goes to the floor, those pistons travel through the corrosion and the lip seals can be ripped. That will lead to a slowly sinking brake pedal when you hold steady pressure on it. When it gets worse, the pedal will go instantly to the floor with no resistance.
Sunday, October 16th, 2011 AT 8:34 PM