Yes, although it's a bit harder to explain. We were sent into Earth's past on a mission, but something went wrong. Something was left behind that alerted United Earth there had been tampering.

When we returned here, there were mutated monstrosities overrunning the island. Most of the locals were dead. It was a ghost town, and it was very difficult to maintain order long enough for the oversight to be cleared up.

I'm well aware how far-fetched this has to sound.