"How could they hit by the lightening with just a tarp? Is there metal attached?"
You don't need metal, just be the highest point in the area.
"You don't need metal, just be the highest point in the area."
Especially if it was wet.
We camped in a valley in the Sierra Nevadas, and there was a lighting strike somewhere in the valley every 30 seconds for a two hour period. We pitched the tent where the boulders around us were at least twice the height of the tent.