'94 blazer brake issues

while driving my brother's blazer the other day, the brake pedal just all of the sudden locked up. I couldn't press it down nor did it budge when I slammed on it. I had to throw it down into first gear so I didn't rear end the car in front of me, and then the pedal went free again? So far, no abs light has come on. There's plenty of fluid in the master cylinder. Any suggestions would be great!

I'm thinking it's a bad power booster....I checked for pinched brake lines, and the actual booster does have vaccuum.

This sounds like a ABS problem. When the pedal goes stiff like that, usually the ABS is engaging. It could be somthing as easy as dirty wheel sensors. The sensors were common to get dirty and cause issues on the older trucks.

hmmm......alright, do you by chance know where the wheel sensors would be located?