The brake grinding sounds a lot like the brake pads are completely worn away and you've got metal on metal. I had that happen on the right front brakes on my van, after making a panic stop while pulling a 7K trailer (with my pickup on it) with pads that were almost worn anyways...after the pads wore all the way out, the metal backing hit the rotor and got so hot that some metal actually melted (and screwed up one of my wheels
)... I got the noise you were talking about immediately after this...and didn't drive the van again 'till I replaced the pads and that rotor...the rotor was completely destroyed!
A stuck parking brake's also possible, I suppose...but I'd bet the brakes there are dead. Hope that helps some...good luck!