Welcome to AF!
Has it happened again? You mentioned that you drove off after it did it. I suspect you have a failed lower ball joint on the lower control arm. You can check it by putting a jack under the control arm and just lifting the tire off the ground. Grip the tire at a 12 oclock and 6 oclock position and try to move it up and down. If you have any play it is the lower ball joint that is bad.
If you aren't handy around cars, I might suggest you take it to a front end specialist and have it aligned. He will check the front end for wear/damage before attempting to align it.