Something going wrong with my brakes

[nguyenSTX]

Randomly when I step on the bakes, the brake peddle won't go down. It last for about a second, but that's long enough to have a few close calls. I also been having an air leak sound coming from my master brake cylinder area (not exactly sure where) when the engine is on and for a few seconds after it's turned off. I can't even pull out my key until the brakes depress after I park. Any suggestions would be great.

I've check the brake fluid, that's all I can think of.
Brake pads were change 10k miles ago.

[Ford_Fixorrepairdaily]

Have them checked out asap.