Braked... and the car won't start again

[constantino_r]

Hi!
My car is a Pontiac Bonneville 1990 SE.
I had been driving for about 4 hours at an average 70 miles an hour when I had to slow down. I began braking little by little, and then the car just turned off, and didn't want to start again.
When I try to start it I hear a sound as if the current doesn't flow. Someone told me it could be a sensor that activates itself when one is driving at high speeds and suddenly brakes, but I don't know if this car has one of those sensors.
Any idea about what could be wrong?
Thank you very much.