I was on my phone when I posted the last response, so let me now expand further.
A brake lining issue would not cause hard braking. If it were indeed a brake line issue the pedal would be very soft. Brakes are hydraulic and vacuum assisted. When the engine shut off you lost your vacuum assist, making it difficult to brake.
If a brake line blew you'd have had a much harder time stopping because the pedal would have went to the floor and the brake wouldn't have been able to grab the rotor due to the loss of hydraulic pressure.
My guess is your alternator may have went, causing your battery to die.