My wife and I went on vacation. While we were gone, my daughter had to move our Fiat 500e out of our driveway to let some contractors into the driveway. The next day, all 4 tires were flat. When I got back, I looked at the tires and couldn't see a slash on them. I started to reinflate each tire. However, when I took the pump off to put the cap on, air came rushing out. I quickly screwed the cap on and saved enough air to drive the car back to our house. The most obvious thing is vandalism, but we don't live in a high crime neighborhood and weren't blocking someone's driveway, and the method seems unusual. Any other possible explanation? Any idea how someone would remove the valves like that? They even put the valve caps back on.