Ethan opened the gate. He used the remote that was on the keyring of Pope's keys. He didn't know about the abbies, so his intention was to drive through the gate to leave Wayward Pines behind. Once he saw the abbie he closed the gate, with a quickness, and kicked the truck in reverse instead.

"If it was his lawn."

Or the suicides could have been a "reckoning" of sorts as punishment for telling the parents…thus proving he/she wasn't worthy of being one of the First Generation.