What Causes Seizure?

I had a seizure for the first time in my life tonight. I was standing, lost control of my body and didnt realise that i was shaking until another person asked if i was ok. It only lasted about 10 seconds i think, but im also feeling very tired and fatigued, Im not sure what could have caused this? I'm trying to dismiss it, but i thought i would ask around for a second opinion. thanks!