this morning i went to start my car, and it turned over, but then died immidiately... i did this a few times, each time it'd turn over, but then die right away, and the 10th time, it turned over and stayed on

anyway, i turned it off, and when i tried to turn it on again, it just died right away again... i had to go to work, so i just took another car, and didn't have time to really look into anything, but anyone have any ideas what could be wrong?!